OAR Box 1107 

Prepped by Ollie Stewart 

Document Number: 

19)V-B-1 

Docket Number: 

A-81-21 

Printed 4/11/2008 3:03:45 PM Sheet 19 of 90 

P.1 
P.2 

, «c l - X 

United States 

Environmental Protection 

Agency 

Office of Air Quality 

Planning and Standards 

Research Triangle Park NC ?' 

Air 

Vinyl Chloride 

Standards: 

Responses to 

Comments on 

January 1985 

Proposed Revisions 

EPA-450/3-86-004 

September 1986 

AH8J-2 

V-B-l 

'•#sm£ ^^^^^^^m^w^m MWiuuiMue ---^^^ ^ a 

J 
P.3 

t .< 

EPA-450/3-86-004 

Vinyi Chloride Standards: 

Responses to Comments on 

January 1985 Proposed Revisions 

Emission Standards and Engineering Division 

U.S. ENVIRONMENTAL PROTECTION AGENCY 

Office of Air and Radiation 

Office of Air Quality Planning and Standards 

Research Triangle Park, NC 27711 

September 1986 
P.4 

*\ 

.•WW r 

This report has been reviewed by the Emission Standards and Engineering Division ofthe Office of Air Quality 

Planning and Standards, EPA. and approved for publication. Mention of trade names or commercial products is 

not intended to constitute endorsement or recommendation for use. Copies of this report are available through 

the Library Services Office (MD-35), U.S. Environmental Protection Agency, Research Triangle Park, North 

Carolina 27711; or, for a fee, from the National Technical Information Services, 5285 Port Royal Road, 

Springfield, Virginia 22161. 
P.5 

VINYL CHLORIDE STANDARD: RESPONSES TO COMMENTS ON 

JANUARY 1985 PROPOSED REVISIONS 

EMISSION STANDARDS AND ENGINEERING DIVISION 

U.S. Environmental Protection Agency 

Office of Air and Radiation 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

SEPTEMBER 1986 

m 
P.6 

TABLE OF CONTENTS 

Section Page 

1.0 SUMMARY • 1-1 

1.1 SUMMARY OF CHANGES SINCE PROPOSAL 1-1 

1.2 SUMMARY OF IMPACTS OF PROMULGATED ACTION 1-3 

2.0 SUMMARY OF PUBLIC COMMENTS AND RESPONSES 2-1 

2.1 GENERAL POLICY AND LEGAL ISSUES 2-1 

2.2 REVISIONS TO RELIEF VALVE DISCHARGE STANDARD 2-10 

2.3 REVISIONS TO LEAK DETECTION AND REPAIR 

REQUIREMENTS 2-22 

2.4 DEFINITIONS 2-41 

2.5 REVISIONS TO OTHER PARTS OF THE STANDARD 2-58 

2.6 MISCELLANEOUS 2-65 

3.0 PETITION FOR RECONSIDERATION 3-1 
P.7 

, rl , (• 

1.0 SUMMARY 

On January 9, 1985, the U. S. Environmental Protection Agency (EPA) 

proposed revisions to the national emission standard for vinyl chloride (VC) 

(50 FR 1182) under authority of Section 112 of the Clean Air Act. The 

standard limits atmospheric emissions of VC from plants producing ethylene 

dichloride (EDC) by the reaction of oxygen and hydrogen chloride with ethylene, 

plants producing VC by any process, and plants producing one or more polymers 

containing any fraction of VC (e.g., polyvinyl chloride (PVC)). The January 9, 

1985, Federal Register notice proposed administrative and clarifying revisions 

to the VC standard based on a review of the standard. 

Public comments were requested on the proposal in the Federal Register 

notice. A total of 16 comment letters were received. Commenters included 

industry representatives, representatives of industry trade organizations, 

State and Federal legislators, one environmental group and one State regulatory 

agency. The public comments are summarized in this document along with 

responses to the comments. The comments and responses serve as the basis for 

changes and clarifications to the revised standard made between proposal and 

promulgation. 

1.1 SUMMARY OF CHANGES SINCE PROPOSAL 

In response to the public comments, one major change and a few minor 

changes and clarifications have been made in the proposed revisions to the VC 

standard. The major change involves the proposed reformatting of the relief 

valve discharge standard. Several comments were received that resulted in 

withdrawal of the proposed requirements for relief valve discharges. 

Other comments resulted in several minor clarifications to definitions 

and other regulatory language. 

1-1 
P.8 

H . 

The revised definition of "EDC purification" in the proposed 

standard has been further clarified by specifically exempting 

intermediate and final product storage. 

The definition of relief valve has been modified to exclude two 

specific pressure control systems: polymerization shortstop 

systems and refrigerated water systems. Also, emissions from 

pressure relief devices that control exhaust gas flow to 

incinerators are not considered relief valve discharges. 

The definition of leak has been clarified by adding the EPA test 

method on which leak measurements are to be based.

 The provision 

specifying that leaks are emissions not regulated under exhaust gas 

provisions has been dropped. 

Three-hour averaging periods have been specified in the 

oxychlorination vent standard and in three other provisions where 

exhaust gas limits are prescribed. (Three-hour averages were 

specified in all other exhaust gas provisions in the proposed 

standard.) 

Certain open-ended lines have been made exempt from Subpart V 

requirements. 

The provision allowing plants to demonstrate effectiveness of 

existing leak detection and repair programs through a performance 

test of a sample of valves has been revised to more clearly indicate 

the number of valves required to be tested. 

Method 601 of 40 CFR 136.3 was approved and incorporated by reference 

for measurement of VC in inprocess wastewater. 

The American Society of Testing and Materials (ASTM) method for 

determining by process sample whether equipment is in VC service 

has been incorporated by reference. 

The definition of connector in Subpart V has been modified to allow 

exemption from reporting and recordkeeping requirements for all 

screwed and welded connectors and flanged connectors that are 

covered by insulation or other materials. 

1-2 
P.9 

1.2 SUMMARY OF IMPACTS OF PROMULGATED ACTION 

No changes in the environmental, energy and economic impacts of the 

standard have occurred since proposal. Further, since no major revisions to 

the standard were proposed, the impacts of the original standard remain 

nc.r,g';"21 "j \i ijp.chaneed. T!"ese imDac^s ar*3 ^""•scribed in ^h^ nr0*^^1 - tp ---s. 

proposed revisions (50 FR 1182). 

1-3 
P.10 

?• n <;i!,vMa."3v O F SUP: rr ""OvviF^'TS A-n •jc-cDnv^rThis document includes responses to public comments on the proposed 

revisions to the VC standard. A list, of the commenters, their affiliations, 

and the EPA docket numbers assigned to their correspondence is given in 

Table 2-1. The comments are organized according tc topic in. the fcllowir.c 

sections. 

2.1 General Policy and Legal Issues 

2.2 Revisions tc Relief Valve Discharge Standard 

2.3 Revisions to Leak Detection and Repair Requirements 

2.4 Definitions 

2.5 Revisions to Other Parts of the Standard 

2.6 Miscellaneous 

2.1 GENERAL POLICY AND LEGAL ISSUES 

Comment Level of Standard 

Six commenters (IV-D-1, IV-D-2, IV-D-6, IV-D-11, IV-D-12, IV-D-13) 

addressed the level of control associated with the VC standard. Three 

commenters (IV-D-1, IV-D-2, IV-D-6) agreed with the EPA's decision not to 

regulate additional sources or change the quantitative emission limits of the 

standard. They alleged no basis exists for making the standard more stringent 

based on health effects, and that there is no new technology which would 

justify a more stringent standard. One commenter (IV-D-6) further stated 

that in light of the EPA's findings that other regulations have been effective 

in reducing VC emissions, a more stringent standard under Section 112 cannot 

be justified. In contrast, four other commenters (IV-D-11, IV-D-12, IV-D-13, 

IV-D-16) stated that the level of the standard would be weakened by the 

2-1 
P.11 

I I 

TABLE 2-1. LIST OF COMMENTERS ON PROPOSED REVISIONS 

TO THE VINYL CHLORIDE STANDARD 

Docket Item Number Commenter and Affiliation 

IV-O-I w. C. Hoi-brook 

The Vinyl Institute 

355 Lexington Avenue 

New York, New York 10017 

Date: March 15, 1985 

IV-D-2 David L. Lull 

Occidental Chemical Corporation 

P.O. Box 699 

Pottstown, Pennsylvania 19464 

Date: March 19, 1985 

IV-D-3 J. C. Ledvina 

Vista Chemical Company 

P.O. Box 19029 

Houston, Texas 77224 

Date: March 21, 1985 

IV-D-4 R. R. Kienle 

Shell Oil Company 

P.O. Box 4320 

Houston, Texas 77210 

Date: March 19, 1985 

IV-D-5 Paul M. King 

PPG Industries, Inc. 

One PPG Place 

Pittsburgh, Pennsylvania 15272 

Date: March 22, 1985 

IV-D-6 John T. Barr 

Air Products and Chemicals, Inc. 

P.O. Box 538 

Allentown, Pennsylvania 18105 

Date: March 20," 1985 

IV-D-7 William T. Newman 

Georgia Gulf Corporation 

P.O. Box 629 

Plaquemine, Louisiana 70765-0629 

Date: March 20, 1985 

aThe docket number for this project is A-81-21. Dockets are on file at 

EPA's Central Docket Section in Washington, D.C. 

2-2 
P.12 

TABLE 2-1 (Continued). LIST OF COMMENTERS ON PROPOSED REVISIONS 

TO THE VINYL CHLORIDE STANDARD 

a 

Dccket Item Number' Commenter and Affiliation 

IV-D-3 T. E. Lingafelter 

Dow Chemical U.S.A. 

2030 Willard H. Dow Center 

Midland, Michigan 4864C 

Date: March 19, 1985 

IV-D-9 Geraldine V. Cox 

Chemical Manufacturers Association 

2501 M Street, N.W. 

Washington, D.C. 20037 

Date: March 25, 1985 

IV-D-10 Charles A. Johnson 

National Solid Wastes Management 

Association 

1730 Rhode Island Avenue, N.W. 

Washington, D.C. 20C36 

Date: March 21, 1985 

IV-D-11 Jeffrey G. Mack 

Delaware House of Representatives 

Dover, Delaware 19904 

Date: March 21, 1985 

IV-D-12 David D. Doniger 

National Resources Defense Council 

1350 New York Avenue, N.W. 

Washington, D.C. 20005 

Date: March 25, 1985 

IV-D-13 Tom Carper 

U.S. House of Representatives 

Washington, D.C. 20515 

Date: March 25, 1985 

IV-D-14 James D. Fannin 

The BF Goodrich Company 

6100 Oak Tree Boulevard 

Cleveland, Ohio 44131 

Date: March 19, 1985 

aThe docket number for this project is A-81-21. Dockets are on file at 

EPA's Central Docket Section in Washington, D.C. 

2-3 
P.13 

TABLE 2-1 (Concluded). LIS'T OF COMMENTERS ON PROPOSED REVISIONS 

TO THE VINYL CHLORIDE STANDARD 

Docket Item Number- Commenter and Affiliation 

17-0-15 W. Eailey Barton 

Borden Inc. 

165 M. Washington Avenue 

Columbus, Ohio 43215 

Date: March 25, 1985 

IV-C-16 Patricia L. Norton 

Louisiana Department of 

Environmental Quality 

P.O. Box 44066 

Baton Rouge, Louisiana 70804 

Date: April 3, 1985 

The docket number for this project is A-81-21. Dockets are on file at 

EPA's Central Docket Section in Washington, D.C. 

2-4 
P.14 

proposed changes and should be made more stringent. One commenter (IV-D-11) 

stated that EPA should replace the standard with one which provides additional 

risk reduction. The other commenter (IV-D-13) argued that the level of the 

standard should be based on the protection of public health and the environment, rather than the ability o**" industry to comply w'th the steward. ~re 

commenter stated the level of the standarc should provide incentive

 for tne 

development of improved emission control systems. 

Response 

These comments relate to how EPA selects the level o" control for 

standards under Section 112 of the Clean Air Act. As noted by these 

commenters, standards set by EPA under Section 112 reflect.the level of 

control necessary to provide an ample margin of safety to protect public 

health. However, in contrast to some of the commenters, EPA believes that 

this level of control must also be achievable to be meaningful and to avoid 

being arbitrary and capricious. The VC standard, established in 1976 as an 

appropriate level of control under Section 112, represented the most stringent 

level of control that can be achieved by VC and PVC plants based on best 

available technologies, while avoiding unreasonable cost. Because the 

revisions to the standard proposed on January 9, 1985, did not substantively 

change the level of control associated with the standard, EPA considered 

these comments in the context of the level of control established in 1976. 

As discussed in mere detail in the following response, EPA concluded that the 

level of control in the VC standard is appropriate. 

Comment Zero Discharge Goal and Consideration of Costs 

Two commenters (IV-D-1, IV-D-6) concurred with the EPA's conclusion that 

Section 112 of the Clean Air Act does not require emissions of VC to be 

eliminated. One of the commenters (IV-D-1) added that the 1977 proposed 

amendments were based on the "erroneous premise" that a zero discharge level 

should be achieved. In contrast, another commenter (IV-D-12) pointed out 

that EPA previously recognized a zero emissions goal. 

2-5 
P15 

Three commenters (IV-D-6, IV-D-8, IV-D-12) addressed the use of costs 

and cost effectiveness in the development of the standard. One commenter 

(IV-D-6) emphasized the importance of a sound, cost-effective regulation. 

The second commenter (IV-D-8) stated that the proposed modifications to the 

standard are aimed at reducing emissions in the most cos

 :>effeet*:we c ?.**.r.e" . 

even though seme new requirements have been added. Conversely, two co^me: - = rs 

(IV-D-11, IV-D-12) objected to the EPA's consideration of costs in developing 

the VC standard. 

P £ S 0 ° C> S ^ 

In the EPA's judgment, the VC standard protects the public health within 

the meaning of Section 112, and EPA may consider cost and feasibility in 

setting the standard. The EPA views are explained in the 1975-76 VC rulemaking, and in the Agency's brief in NRDC v. LPA, No. 85-1150 (D.C. Cir). 

The NRDC/EDF provided no new information on this issue. 

Comment Emission Standards vs. Equipment arid Work 

Practice Standards 

The commenter (IV-D-16) stated that uncertainties in the existing 

standard have required enforcement personnel to develop enforcement policies 

outlining the level of effort expected of plants for compliance. The commenter 

recommended that revisions to the standard specify required equipment and 

operating practices for meeting the existing limits. Revising the standard 

in this manner would ensure continued strict control of VC emissions while 

providing industry and enforcement personnel with specific guidance on 

required level of effort. The result would be more effective enforcement of 

the standard. 

Response 

Under the requirements of the Clean Air Act, as amended, EPA is to set 

emission (i.e., performance) limits wherever possible and to allow the owners 

an'd operators of affected facilities to achieve that limit in any way 

available. In the case of VC emissions, it is both possible and appropriate 

1-6 
P.16 

to" establish an emission limit for most sources. Thus, EPA can not require 

the use of specific types of equipment for most of the sources covered by the 

standard. However, where it is not practicable to set an emission standard, 

EPA has required the use of equipment and other work practices. 

Comment Evidence of Human Health Risk 

One commenter (IV-D-1) questioned the need for a standard regulating VC 

emissions on the basis of health risks, citing the absence of human deaths 

related to VC exposure in the vicinity of regulated plants. Another commenter 

(IV-D-14) stated that the absence of predicted cancer cases caused by VC 

exposure are proof of the success of the VC standard. 

Response 

Generally, the absence of specific evidence linking human deaths related 

to VC emissions to the environment is not indicative of the absence of risk 

from these emissions. At the time the original VC standard was developed, 

unit risk factors were developed based on studies of the health effects from 

exposure to VC emissions. These health studies implicated instances of liver 

angiosarcoma, other cancers, and noncarcinogenic disorders in animals from 

inhalation of VC. While there have been no recent epidemiological studies 

relating to exposure to VC emissions, instances of liver angiosarcoma in 

individuals exposed to VC have been reported. As part of the review of the 

VC standard, the EPA carcinogen assessment group reviewed the original health 

studies and subsequent health information which confirmed the link between VC 

exposure and brain and liver cancer. The review concluded that the health 

effects associated with VC and the risk estimates developed at the time of 

the original standard remain valid. 

To the extent that the original VC standard has been effective in 

reducing or eliminating incidences of cancer due to exposure to VC, then the 

efforts of EPA, industry and individuals in controlling VC emissions have 

been successful. However, given the latency period for health effects and 

the existence of confounding variables in exposure and development of cancer, 

both the Agency and industry should continue to make reasonable efforts to 

continue controlling VC emissions. 

2-7 
P.17 

Comment Technology Demonstration Requirements 

One commenter (IV-D-12) stated that there is no language in Section 112 

which would require a control technology or emission level to be demonstrated 

in order to serve as the basis of a NESHAP. The commenter pointed to the 

statement in the preamble that "10 ppmv represents the lowest level of 

control which has been consistently achieved" as indicative that EPA was 

applying such a requirement in evaluating alternative exhaust gas limits. 

The commenter stated that the requirements of Section 112 are intended to be 

technology forcing, based on projections of the capabilities of technology 

rather than on past achievements. 

Response 

The VC standard was established at a level which was determined to be 

achievable using best available control technologies. The data on VC emissions 

control indicate that a 5 ppm emission limit would not be consistently 

achievable, and EPA selected a 10 ppm emission limit to reflect the level of 

control required by tha standard. In doing so, EPA considered both the 

feasibility of this level of control and the health impacts resulting from 

this control level including that the standard provides an ample margin of 

safety for public health. 

Comment Withdrawal of 1977 Proposal 

Three commenters (IV-D-4, IV-D-7, IV-D-14) stated their support for the 

EPA's withdrawal of the 1977 proposed amendments to the standard. 

Response 

As discussed in the preamble (50 FR 1183), EPA did not believe it was 

appropriate to leave the proposed amendments to the VC standard in effect or 

to promulgate amendments based on the proposed amendments. This decision was 

the outcome of a review procedure that considered the 1977 proposal, as well 

as a recent reevaluation of existing and new control technologies, of VC 

sources not regulated by the standard and of enforcement and compliance 

experience since promulgation of the standard. 

2-8 
P.18 

Comment Effectiveness of VC Standard 

One commenter (IV-D-14) stated that the industry has effectively 

implemented the VC standard as evidenced by the fact that actual VC emission 

reductions under the standard have exceeded the original standard estimates. 

Another commenter ^IV-D-15) also stated that the VC standard lias been 

successful in greatly reducing VC emissions, ane pointed ci:t the considerac1? 

expense to plants in Louisiana to install control equipment and implement 

operatinq procedures to meet the standard. 

Resoonse 

No response necessary. 

Comment Clarification of Preamble and Regulation 

Three commenters (IV-D-1, IV-D-6, IV-D-9) stated that the explanation cf 

the standard contained in the preamble and the language of the standard 

itself need to be clarified and made more consistent. One commenter (IV-D-1) 

suggested that the interpretative language of the preamble be incorporated 

into the standard, where appropriate, to help ensure consistent interpretation. 

The commenter stressed the importance of resolving uncertainties associated 

with the standard to prevent unnecessary cost to the industry and EPA. A 

second commenter (IV-D-6) also emphasized the need to remove all ambiguity 

from the standard to prevent the costs of negotiation and litigation caused 

by differing interpretations of the standard. 

Response 

One purpose of the proposed revisions was to enhance the clarity of the 

requirements of the VC standard. All specific instances of confusion over 

provisions of the standard and the language of the preamble cited by the 

commenters have been addressed in other responses directed toward the relief 

valve definition, the leak detection requirements, the applicability cf the 

standard to storage tanks, the three-hour averaging period, and other issues. 

The EPA believes that with these clarifications the requirements of the 

standard are clear and consistent with the intent of this action. 

2-9 
P.19 

Comment Need to Update Standard 

The commenter (IV-D-14) emphasized the need to update the standard based 

on eight years of experience by EPA and industry since promulgation of the 

standard. He noted that EPA has effectivelv analyzed experience under trie 

Resoonse 

cevelcoir.n rev -'s i :ns 

Mo response necessary. 

Comment .Author-'t*-' for Work Prcctia Standard; 

The commenter (IV-D-1) restated industry's position during the original 

rulemaking that EPA had no legal authority at that time to promulgate work 

practice rules. 

Response 

What the Agency's authority was in 1976 is not a subject of this 

rulemaking. 

2.2 REVISIONS TO RELIEF VALVE DISCHARGE STANDARD 

2.2.1 Numerical Limit Format 

Comment Numerical Limit Format 

Seven commenters (IV-D-2, IV-D-7, IV-D-9,.IV-D-12, IV-D-13, IV-D-14, 

IV-D-16) addressed the numerical limit format selected for the relief valve 

discharge standard. 

Four commenters (IV-D-11, IV-D-12, IV-D-13, IV-D-16) objected to the 

proposal to grant an allowable relief valve discharge rate. One of these 

commenters (IV-D-=16) stated that although the proposed revised relief valve 

discharge requirements more clearly specify which relief valve discharges are 

in violation of the standard, they do not penalize discharges which may be 

caused by gross negligence. The second commenter (IV-D-12) urged EPA to 

retain the existing standard that relief valve discharges are violations of 

the standard unless unpreventable. The commenter stated that EPA has presented 

2-10 
P.20 

no analysis of the "significant" burden on Agency resources which was cited 

as one reason for the proposal. Further, the commenter stated that preventable 

discharges should be avoided as a matter of principle, and pointed out that 

relief valve discharges are the sincle largest remaininq source of VC emissions 

at some plants. Finally, the commenter objected to the allowable discharge 

provision as being a significant weakening of the standard since current EPA 

enforcement policy has routinely concluded that the vast majority of releases 

are preventable. The commenter expressed concern that the numerical limits 

would legitimize the current discharge rates by industry, regardless of the 

ability tc lower them further.

 The third commenter (IV-D-13) stated that the 

proposed numerical standards are not consistent with the Congressional intent 

for the regulation of hazardous substances. The commenter pointed out that 

the proposed standards would be less stringent than the requirements of a 

consent agreement reached in a recent case against Formosa Plastics in 

Delaware. The commenter stated that the recent relief valve discharge 

performance of the Formosa Plastics facility would not have been affected by 

the proposed standard, even though it was the top VC emitter in the country. 

Both commenters IV-D-11 and IV-D-12 urged EPA to drop the proposed revisions 

and to develop more stringent requirements for relief valve discharges. 

Four commenters (IV-D-2, IV-D-7, IV-D-9, IV-D-14) expressed general 

support for the EPA's proposal of numerical limits. One of these commenters 

(IV-D-14) stated his belief that the proposed numerical limits for relief 

valve discharges are practical but sufficiently stringent to require further 

progress by industry in preventing discharges. Another of these commenters 

(IV-D-2) further urged EPA to adopt an enforcement policy of reviewing all 

relief valve discharge incidents in excess of the limits and suspending 

enforcement if those incidents were deemed to be emergencies. 

Response 

At the time the original VC standard was developed, it was recognized 

that relief valves and other safety relief devices are a potential source of 

VC emissions which are controllable through a combination of equipment and 

work practices. However, information was not available on the effectiveness 

2-11 
P.21 

of control measures on relief valve discharge performance. The original 

standard regulated relief valve discharge emissions by prohibiting all 

nonemergency discharges. Emergency discharges are described as those which 

could not have been avoided by taking measures to prevent the discharge. 

This standard is an emission or performance standard that limits all VC 

emissions except those resulting from emergency discharges. 

During the review of the VC standard begun in 1980 and completed in 

1982, including enforcement and compliance experience under the VC standard. 

EPA enforcement personnel reported significant manpower and resource requirements were being used to monitor compliance with the relief valve discharge 

standard. Ihis was primarily due to the effort required to individually 

evaluate each relief valve discharge for preventability. The review study 

also found that many producers were uncertain about whether they complied 

with the relief valve discharge standard. The review study concluded that 

the format of the standard should be reviewed, primarily to reduce the 

enforcement burden on EPA and to improve industry's understanding of compliance requirements. Based on the recommendations of the review study, EPA 

set out to establish a standard for relief valve discharges based on numerical 

discharge limits reflecting performance representative of compliance with the 

original standard. The results of this effort to reformat the relief valve 

discharge standard were proposed in January 1985 (see 50 FR 1182). 

In response to comments objecting to the proposed revised relief valve 

discharge requirements, EPA has reconsidered the proposed action to add new 

numerical limits for relief valve discharges. In particular, EPA has reviewed 

the basis for the review study recommendations that the format of the standard 

be changed (i.e., to reduce enforcement burden and to improve understanding 

of compliance requirements). During the five years since the review study 

was conducted, efficiency of activities relating to the enforcement of relief 

valve discharge standard has improved. This is due in large part to experience 

established over the last 5 years in enforcing the original standard. As a 

result, EPA enforcement personnel consider this standard to be much less 

resource and manpower intensive. Furthermore, enforcement actions taken by 

EPA against a number of plants since the time of the review study have served 

2-12 
P.22 

two purposes. First, they have resulted in improved control of relief valve 

discharges accompanied by a reduction in relief valve discharge emissions. 

Second, some of these enforcement actions have resulted in consent decrees 

which outline specific measures required to be taken by the individual plant 

f.tr comol ia nee turooses ~hese consent decrees net only serve to clari~v 

compliance requirements for the subject plant but serve as guidelines for a!1 

plants of the types of measures deemed appropriate by EPA for controlling 

relief valve discharges. In this way, understanding of compliance requirement: 

has been appreciably improved. Because these recent findings tend to invalidate the maicr conclusions cf the review studv EPA bei ieves it is r.c longer 

appropriate to reformat the original standard. Consequently, the proposed 

numerical limits for relief valve discharges, are not being promulgated. 

2.2.2 Level of Numerical Limits 

Comment Cap on Mass Emissions, 100-Pound 

De Minimus Exemption 

The commenter (IV-D-13) stated that the revised relief valve discharge 

limits should also include a cap on the size of discharges so that the 

quantity of VC emitted is regulated in addition to the frequency of discharge 

events. 

Two commenters (IV-D-2, IV-D-7) recommended that relief valve discharges 

less than 100 pounds be exempted from the revised relief valve discharge 

requirements. One of the commenters (IV-D-7) emphasized the small environmental impact of brief relief valve "chatter" incidents. The. second commenter 

(IV-D-2) stated that the administrative burden and personnel requirements for 

investigating, documenting, reporting, and negotiating minor discharges are 

disproportionate to the corresponding hazard to human health. 

Response 

As discussed in Section 2.2.1, EPA has decided not to reformat the 

original standard with numerical limits. The original relief valve discharge 

standard provides for review of all discharges, including both large and 

small discharges. Any relief valve discharge which is preventable is in 

violation of the standard and subject to enforcement. 

2-13 
P.23 

Comment Numerical Limit Applied to EDC/VC Production Units 

Three commenters (IV-D-1, IV-D-5, IV-D-14) provided recommendations on 

applying the relief valve discharge limit for EDC/VC plants to multi-unit 

complexes and expanded plants. Commenter IV-D-1 requested that the limit of 

4 discharges ?er year te applied to each individual production unit within a 

plant. Commenter IV-D-5 suggestec that the l^'mit be applied separately to 

each discrete plant under separate management in a multi-plant complex. 

Commenter IV-D-1 a"so recommended that the relief valve discharge limit be 

applied to each new EDC/VC production unit added to an existing facility. 

Alternat^'ely, Commenter IV-D-1 agreed w'th the suggestion of another commentes 

(IV-D-14) that the limit for expanded EDC/VC plants be increased in proportion 

to the increase in production capacity. 

Response 

As discussed in Section 2.2.1, EPA has decided not to revise the relief 

valve discharge requirements by adding numerical limits. As done currently, 

EPA will continue to evaluate the preventability of each discharge. 

2.2.3 Control Measures 

Comment Equipment Requirements in Relief Valve 

Discharge Standard 

The commenter (IV-D-16) requested that the revised standard delineate 

the types of measures considered adequate to prevent unnecessary discharges 

from relief valves and failed equipment. In particular, the commenter 

(IV-D-16) recommended that a provision be added to the standard requiring a 

level of redundancy for any equipment and control instrumentation which 

influence operating pressures so that failure of a single equipment piece or 

control instrument does not cause a relief valve discharge from 

overpressurization. 

Response 

Ihe approach recommended by the commenter is inappropriate in this case. 

The Clean Air Act, as amended, requires EPA to establish emission standards 

2-14 
P.24 

(i.e., performance standards) unless they are not feasible to prescribe or 

enforce. Thus, because EPA can establish an emission/performance standard, 

such as a standard prohibiting all relief valve discharges except emergencies, 

EPA is reouired to do so. Information on the effectiveness of various 

equipment and operational procedures for controlling relief valve discharges 

was not available at the time the original standard was written. It-was 

expected that different combinations of control measures would be equally 

effective in preventing relief valve discharges. One finding of the review 

study was that individual "control techniques" (including equipment and 

operational measures; associated with prevention of relief valve discharges 

can not be directly related to emissions reduction. Furthermore, the attitude 

of plant owners and operators appears to be an important factor in controlling 

relief valve discharge occurrences. During visits to five PVC plants with 

good performance records, EPA learned that these plants had effectively 

implemented different combinations of equipment and work practices for 

preventing relief valve discharges (Docket Item II-B-31). Based on these 

findings, EPA continues to believe that it is more effective to allow plants 

to develop their own combination of preventive measures that will enable them 

to eliminate preventable discharges limits rather than to prescribe control 

measures. 

The EPA agrees that redundant instrumentation and certain other eauipment 

are an important factor in prevention of relief valve discharges at some 

plants. However, the level of redundancy varies according tc plant and the 

type of discharge to be controlled and cannot be uniformly specified for all 

plants. Generally, at least one level of redundancy for key instrumentation 

and equipment affecting relief valve discharge incidence is considered by EPA. 

to be necessary for proper operation and maintenance. 

Comment Gasholder Containment System 

Two commenters (IV-D-11, IV-D-12) urged EPA to strengthen the standard 

by specifying the use of all available equipment and practices to minimize 

emissions, particularly gasholders. One of the commenters (IV-D-12) stated 

that gasholder containment systems are feasible and should not be rejected on 

2-15 
P.25 

the basis of cost or the small quantity of emissions that would be controlled 

through a gasholder system. The commenter asserted that cost is an inappropriate factor for consideration under Section 112 and that gasholder 

containment systems have been installed pursuant to enforcement actions. 

Further, the commenter stated that VC emissions control through the use o~ 

gasholder containment systems should be pursued, even if they are only 

effective in controlling emergency releases of VC. 

The second commenter (IV-D-11) stated that EPA should examine the use cf 

gasholder containment systems on PVC plants to contain releases of VC. This 

commenter pointed out that such a system is being required

 for a PVC pi ?..'*.' -> 

Delaware pursuant to a consent decree. 

Response 

Gasholders are one of many control measures that are available to plants 

to control relief valve discharge emissions. In fact, some plants currently 

have gasholders available as part of the VC recovery system or as a surge 

vessel feeding the incinerator or other primary control device (Docket Item 

II-A-19). At least one PVC plant vents relief valves on certain equipment 

(i.e., equipment other than reactors and storage spheres) to a gasholder 

(Docket Item II-B-31). The EPA is unaware of any plant that currently vents 

relief valves on PVC reactors directly to a gasholder. 

Although gasholders may be appropriate technology for certain plants to 

reduce relief valve discharge emissions, they are not essential control 

technology for all plants, as evidenced by the fact that some plants with the 

lowest relief valve discharge rates do not have gasholders. Consequently, 

EPA believes it is inappropriate to require gasholders for all plants. 

However, EPA does not discourage the use of gasholder containment systems as 

a control technology for relief valve discharges when appropriate. 

2.2.4 Applicability of Numerical Limits 

Comment Multiple Discharges During Single 

Overpressure Event 

Three commenters (IV-D-1, IV-D-3, IV-D-6) requested that multiple relief 

valve discharges that occur from the same piece of equipment because of a 

2-16 
P.26 

single overpressure event be considered a single discharge regardless of 

whether they occur simultaneously. 

Response 

This comment refers to the method for counting discharges under the 

proposed revised requirements for reiief valve discharges which EPA has 

decided not to promulgate (see Section 2.2.1). The number of relief valves 

that discharge during an overpressure event is not critical to compliance 

determinations under the current standard. 

Comment Discharges Vented to a Control Device 

Iwo commenters (IV-D-1, IV-D-14) requested additional clarification on 

the applicability of the relief valve discharge limits to discharges that are 

vented to a control device. One commenter (IV-D-1) suggested the limits 

specify that only discharges direct to the atmosphere are to be considered 

when determining compliance with the limits. The second commenter (IV-D-14) 

questioned whether a relief valve discharge vented to a control device not 

meeting the 10 ppm limit would be counted as a relief valve discharge for 

compliance purposes. He expressed concern that both a 10 ppm violation and a 

relief valve discharge violation could be cited if the standard does not 

clearly indicate that relief valve discharges conveyed to a control device 

are no longer considered to be relief valve discharges regardless of whether 

10 ppm is achieved. 

Response 

As with the previous comment, this comment refers to the method of 

determining which relief valve discharges are subject to the numerical 

discharge limits. Although EPA has decided not to revise the relief valve 

discharge standard (see Section 2.2.1), the discussion on which discharges 

are subject to the standard remains valid. Specifying that only relief valve 

discharges direct to the atmosphere are to be considered relief valve discharges for compliance purposes is inconsistent with the tPA's intent. 

Relief valves that discharge to headers that ultimately discharge to the 

2-17 
P.27 

atmosphere without control are clearly intended by EPA to be relief valve 

discharges subject to the standard. 

As explained in the preamble to the proposed revisions (50 FR 1189), 

relief valve discharges that are vented to a control device meeting 10 ppm 

ar- exempt from the relier \alve discharge standard. Analyses incicate thr..*-

a 99.9 percent reduction in VC content is achievable when a relief valve 

discharge is vented through a control device designed to reduce emissions to 

10 ppm. Consequently, althcugh it is not feasible to vent all relief valve 

discharges to a control device, benefits in emission reductions are attainable 

in many cases. Therefore, the EPA supports and encourages the venting cf 

relief valve discharges to a control device as long as such venting does not 

interfere with the ability of the control device to reduce exhaust gas 

emissions to 10 ppm. In the event that a relief valve discharge is vented tc 

a control device while it is not meeting 10 ppm, both the standards for 

exhaust gas and relief valve discharges are applicable. 

2.2.5 Compliance Method 

Comment Batch Production Rate at Bulk Plants 

Two commenters (IV-D-1, IV-D-2) requested that the relief valve discharge 

compliance method for bulk PVC plants be changed to allow separate counting 

of prepolymerization and postpolymerization batches. 

Response 

This comment is not relevant because it refers to counting of batches 

for demonstrating compliance with proposed limits on the number of discharges 

per 100 batches. As discussed in Section 2.2.1, EPA has decided not to 

revise the relief valve discharge standard. 

Comment . Effect of Batch Production Rates 

One commenter (IV-D-1) stated that the method for determining compliance 

with the relief valve discharge limits for PVC plants unduly penalizes plants 

whose batch production rates are slightly less than the exact number of 

batches needed to qualify for the next integer of permitted discharges. The 

2-18 
P.28 

commenter alleged that the method is unfair because business conditions alone 

determine how many batches a plant makes. A. second commenter (IV-D-15) also 

pointed out the penalty to plants operating at low capacity (less than 2,858 

batches per year) such that a single discharge would violate the limit. 

Response 

As with the previous comment, this comment is not relevant because EPA 

is no longer planning to measure compliance with the relief valve discharge 

standard at PVC plants based on a number of allowable discharges per batch 

production rate. 

Comment Rounding of Calculated Discharge Frequency 

One commenter (IV-D-2) objected to the "preciseness" of the proposed 

relief valve discharge limits and requested clarification on how rounding 

would be used to compare calculated discharge frequencies to the limits. 

Response 

As with previous comments, this comment is no longer relevant. 

Comment Low Batch Rate Provision 

Three commenters (IV-D-1, IV-D-9, IV-D-14) recommended alternative 

language for the proposed provision in 40 CFR 61.65(a)(l)(iii) pertaining to 

allowable discharges at low batch production PVC plants. 

Response 

As with previous comments, this comment is no longer relevant. 

Comment 2-Year vs. 12-Month Compliance Period 

Three commenters (IV-D-1, IV-D-2, IV-D-6), pointed out that the relief 

valve discharge limits are based on two years of performance data but are 

applied on an annual basis. Accordingly, two of the commenters (IV-D-2, 

IV-D-6) stated that a 2-year compliance period would be more appropriate. 

2-19 
P.29 

Response 

As with previous comments, this comment is no longer relevant. 

Comment Fixed 12-Month Compliance Period 

Two commenters 'IV-D-8, IV-D-9) recommended that the compliance period 

for relief valve discharges be changed from a 12-mcnth period rolling every 

6 months to a fixed 12-month period to ensure that the same discharge or 

group of discharges are net counted towards more than one exceedence. 

Response 

As with previous comments, this comment is no longer relevant. 

Comment Alternative Regulation Format 

The commenter (IV-D-2) suggested that the basis of prescribing the 

relief valve discharge limits for PVC plants be revised by adopting "a system 

of permitted discharges, expressed as whole integers, for increasing increments of ranges of number of batches polymerized: 2,858 to 5,716; 5,716 to 

8,754; etc." 

Response 

As with previous comments, this comment is no longer relevant. 

2.2.6 Reporting Requirements 

Comment 10-Day vs. Quarterly Report 

Three commenters (IV-D-12, IV-D-13, IV-D-16) objected to the change in 

relief valve discharge reporting requirements from 10-day to quarterly 

reporting. Two of the commenters (IV-D-12, IV-D-13) stated that a shorter 

reporting period would alert State, Federal and local officials as well as 

the public of VC releases sooner. Commenter IV-D-12 urged adoption of a 

24-hour reporting requirement as consistent with requirements of the 

Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), 

The third commenter (IV-D-16) explained that the current practice for enforcement personnel to complete investigations of discharges within 45 days of the 

incident has been mutually advantageous to industry and enforcement personnel. 

2-20 
P.30 

Response 

The EPA has reviewed enforcement data and agrees with the commenters 

that retention of the 10-day reporting requirement is desirable. Federal, 

State and local officials promptly review these reports and use the informatioi 

contained therein in enforcement activity to aid in the prevention o**' repeat; 

incidents. Allowing a longer reporting period would net only make it more 

difficult to investigate a release because of the passage of time, but would 

unnecessarily delay appropriate action by the enforcement agency and possibly 

also the source. Further, 10 days is a sufficient time for sources to gather 

the needed information to prepare a report. 

A 24-hour reporting requirement was not selected. The EPA. believes that 

the benefits of the 10-day reports would not be significantly increased by 

24-hour reporting. Also, at least one State already requires its source to 

report discharges by telephone within three hours. The EPA feels that other 

States may also include the requirement if the need and enforcement resources 

exist. Owners and operators should review and consider the need to report 

emissions of VC as they relate to the Comprehensive Environmental Response, 

Compensation and Liability Act (CERCLA). In particular, emissions of VC not 

allowed by the VC standard and greater than the CERCLA "reportable quantity" 

may need to be reported to the National Response Center. 

2.3 REVISIONS TO LEAK DETECTION AND REPAIR REQUIREMENTS 

2.3.1 Need for Subpart V in VC Standard 

Comment Reauest to Drop Subpart V 

Several commenters urged dropping the addition of Subpart V in the VC 

standard. 

Five commenters (IV-D-4, IV-D-3, IV-D-5, IV-D-14, IV-D-15) stated that 

existing leak detection and elimination programs are at least as effective as 

Subpart V in controlling equipment leaks. According to these commenters, 

applying Subpart V to the VC industry is not justified because emission 

reduction would be insignificant and no health benefit would result. Furthermore, Subpart V would create additional administrative burden that would 

necessitate an increase in resource and manpower requirements. 

2-21 
P.31 

Two commenters (IV-D-3, IV-D-12) stated that incorporation of Subpart V 

in the VC standard could potentially result in less stringent control of 

equipment leaks because some plants have existing leak detection and elimination programs with more stringent leak definitions than Subpart V. Commenter 

IV-D-12 urged EPA to prepare and make public a pcint-by-point analysis 

comparing existing leak detection and elimination programs to requirements ir 

Subpart V. 

Response 

The original VC stancard required implementation of a formalized prog ran; 

for detection of leaks from equipment in VC service and elimination of these 

leaks. This program was based on an area-wide monitoring system and routine 

use of a portable monitor to detect leaks. Detailed requirements for these 

leak detection and repair programs were not specified; rather, plants were 

required to develop their own plans subject to approval. During the review 

of the original standard, EPA found that existing leak detection and repair 

programs implemented by plants vary significantly from plant to plant (Docket 

Item II-A-19). While some of the differences in these programs resulted from 

site-specific differences in plants (e.g., layout of plant, background 

concentration, etc.), others resulted from ineffective approaches to routine 

leak detection and repair. For example, differences in plant programs 

include variations in leak definitions and monitoring practices. Leak 

definitions used in conjunction with portable monitors are yery stringent (10 

to 25 ppm) at some plants, while some plants have no specific leak level 

defined for portable monitors. Some leak definition concentration levels 

were comparable to the 10,000 ppm used in the routine program of Subpart V 

but were based on measuring the leak at a distance from the equipment rather 

than at the surface (leak interface) of the equipment as required by Subpart V. 

Similarly, some plants routinely monitor equipment components for leaks with 

a portable monitor on a formal schedule, while others monitor for leaks only 

when indicated by an area monitor detection. These differences can significantly affect the effectiveness of leak detection and repair programs. Based 

on these findings, EPA concluded that more specific leak detection and repair 

2-22 
P.32 

requirements should be established for certain equipment in VC service. The 

EPA did not propose to change the level of control (emission or risk reductions 

or cost implications) with this part of the VC standard as some commenters 

indicated, but instead proposed to provide a better way to evaluate compliance 

with the original decision to require effective leak detection and elimination. 

As noted in the preamble to the proposed revisions (50 F?. 1190), studies 

conducted by EPA and industry in conjunction with development of equipment 

leak standards for other industries have provided information on what constitutes an effective program for detecting and repairing equipment leaks since 

the VC standard was first developed in 1975 and 1976. Based on these studies, 

EPA selected equipment and work practice requirements that represent an 

effective leak detection and repair program and included them in 40 CFR Part 

61 Subpart V. This subpart, promulgated on June 6, 1984, established leak 

detection and repair requirements for equipment in volatile hazardous air 

pollutant (VHAP) service. These requirements were specifically developed to 

regulate emissions of hazardous pollutants such as benzene and are equally 

applicable to VC. Accordingly, EPA proposed to designate VC as a VHAP in the 

context of Subpart V. Addition of Subpart V to the VC standard would ensure 

effective control of equipment leaks on a consistent basis throughout the VC 

and PVC industries. (It should be noted that new, modified, or reconstructed 

VC production and recovery plants are covered by the new source performance 

standard for the organic chemical industry. This standard for VOC emission 

is essentially identical to Subpart V.) The basis for adding Subpart V to 

the VC standard was explained in detail in the preamble to the proposed 

revisions (50 FR 1190-92). 

Prior to the January 9, 1985, proposal, EPA requested and then responded 

to industry comments by adjusting how Subpart V is to be applied under the VC 

standard. At that time, industry comments emphasized the effectiveness of 

existing leak detection and repair programs resulting from compliance with 

requirements of the VC standard and OSHA regulations. The industry commenters 

suggested that Subpart V be required only for those plants with inferior 

programs. While Subpart V already provides alternative standards for reducing 

the burden on plants with effective leak detection and repair programs (see 

•23 
P.33 

40 CFR 61.243), industry representatives pointed out that even the alternative Subpart V requirements would require plants to inventory equipment 

components in VC service, an unreasonable administrative burden according to 

the industry commenters. Even though EPA finds it difficult to understand 

how an effective program can exist without an equipment inventory, EPA 

responded to the industry concerns in the January 9, 1985, proposal by 

allowing plant owners and operators to determine compliance with the alternative standards in Subpart V by testing a prescribed sample of all valves, 

thereby reducing significantly the administrative burden associated with 

inventorying VC service equipment. 

The EPA disagrees with the comment that Subpart V could result in less 

stringent control of equipment leaks than existing programs. In general, 

Subpart V represents a better way to determine compliance with requirements 

for leak detection and repair. In contrast to the provisions for leak 

detection and repair programs in the original VC standard, Subpart V contains 

a detailed list of requirements that, once implemented, will result in 

effective control of equipment leaks at reasonable cost. Any plants with 

effective existing programs based on more stringent leak definitions or 

monitoring practices than Subpart V will continue to effectively control 

equipment leaks either by implementing Subpart V or continuing with their 

existing program. Any increase in equipment leak emissions caused by plants 

switching to Subpart V would be more than offset by additional reductions 

achieved at plants with programs less effective than Subpart V. In this way, 

the overall level of control of equipment leak emissions would not be changed 

by incorporation of Subpart V in the VC standard. 

2.3.2 Applicability of Subpart V Under VC Standard 

Comment Option to Implement Subpart V 

Two commenters (IV-D-2, IV-D-14) recommended that the regulation clearly 

specify that plants may elect to implement Subpart V or continue their 

existing leak detection and elimination program supplemented to demonstrate 

that less than 2 percent of valves in VC service are leaking. Similarly, 

another commenter (IV-D-6) requested that the regulation clearly indicate 

2-24 
P.34 

that plants demonstrating that less than 2 percent of valves are leaking are 

not subject to Subpart V. A third commenter (IV-D-14) also recommended that 

plants be given the option of continuing existing programs or complying with 

Subpart V, explaining that such an option is appropriate in the absence of 

justification that Subpart V is more effective than existing programs. 

Response 

The EPA. will use Subpart V, as reeded, to supplement determinations cf 

compliance with the requirements of §61.65(b). Because Subpart V dees not 

address some sources covered under 561.65(b), Subpart F will serve as the 

•main basis for determinations of compliance for these sources. For example, 

Subpart V does not address loading or unloading lines (except to the extent 

such lines are open-ended lines or valves) and, therefore, the requirements 

of §61.65(b)(1) will be used to evaluate compliance. Other sources covered 

by §61.65(b) (e.g., pumps) are also covered by Subpart V. For these sources, 

Subpart V will be used to supplement Subpart F when EPA makes compliance 

determinations. The EPA decided to propose and promulgate this approach 

because, while- the work practices and equipment requirements of Subpart F 

specify the goal of the original standard, it did not always clearly specify 

how to achieve acceptable compliance. For example, the requirements for 

pumps [§61.65(a)(3)(i)l require double mechanical seals or equivalent. 

Subpart V goes oh to define compliance for all the known equivalent systems 

for pumps: other dual seal systems and leakless pumps. The only aspect of 

Subpart F where compliance determinations would be substantially changed 

concerns the routine leak detection and repair requirements of 

§61.65(a)(8)(ii). The basis for this decision is discussed in the previous . 

response and is needed to spell out clearly how compliance is determined. In 

making this change EPA considered options, as requested by industry commenters, 

before the standard was proposed and selected an approach as discussed below. 

The option recommended by the commenter of continuing the existing leak 

detection and elimination program or complying with the Subpart V monitoring 

and repair requirements for valves is already offered in the revised standard, 

but only for plants who initially, annually, and at the request of EPA 

2-25 
P.35 

demonstrate that less than 2 percent of the prescribed sample of valves are 

leaking. Plants failing the performance test at any time may nc longer elect 

the option of only continuing their existing program and performing an annual 

test. Removal of this option is net unreasonable because failure of the 

performance test is indicative that improvement in leak detection and rep?.';' 

techniques is needed and warranted. Such improvement is provided by the 

requirements of Subpart V. However, plants required to comply with all 

requirements of Subpart V may be able to perform annual leak checks instead 

of more frequent monitoring. This is possible because Subpart V contains 

alternative provisions exempting valves from routine monitoring requirements 

if an annual test demonstrates that less than 2 percent of valves are leaking. 

Comment Additional Equipment Requirements Under Subpart V 

Three commenters (IV-D-1, IV-D-8, IV-D-9) noted that the EPA's conclusion 

that all equipment except valves and flanges are already controlled to a 

level consistent with Subpart V is not adequately reflected in the proposed 

regulation. The commenters recommended that the inconsistencies in requirements of Subpart V and the VC standard be clarified by listing which 

requirements apply to specific equipment. 

In particular, several commenters (IV-D-1, IV-D-2, IV-D-3, IV-D-4) 

pointed out that Subpart V contains requirements for sensors on pump seals 

not found in the VC standard and that under the revised standard, plants 

would be required to retrofit pumps with seal sensor devices at significant 

cost. One of the commenters (IV-D-3) also stated that compliance with the 

open-ended valve requirements of Subpart V would require retrofit expenditure. 

Another commenter (IV-D-2) expressed concern about the cost cf performing 

annual leak checks on valves, many of which are reportedly difficult to 

access. Three commenters (IV-D-1, IV-D-2, IV-D-4) stated that the area 

monitors operated under the VC standard provide adequate leak detection for 

seal failures. 

2-26 
P.36 

Response 

As stated in the preamble to the proposed revisions (50 FR 1191), 

addition of Subpart V to the VC standard substantively affects only valves 

and flanges in VC service. More specifically, even though Subpart V will te 

used tc suDplement compliance determinations with only the equipment leak 

requirements in Subpart F, plants complying with the eouipment and work 

practice requirements of Subpart F for equipment components other than valves 

and flanges .should automatically comply with the Subpart V provisions. 

Requirements in 40 CFR 61.65(b) of Subpart F for valves, pumps, compressors, 

and leakage from relief valves are consistent with requirements in Subpart 7. 

Despite the concerns raised by the commenters, this conclusion is still 

judged by EPA to be essentially correct with the following exception. 

For those plants that have not already adopted the usual industry 

practice of capping open-ended lines, Subpart V -will require these lines to 

be capped. Capping of open-ended lines is required both in Subpart V for 

controlling equipment leaks of volatile hazardous air pollutants and in the 

SOCMI equipment leak standards (40 CFR Part 60 Subpart VV). In both cases, 

capping open-ended lines was judged to be a cost-effective method for eliminating leaks from open-ended lines. The cost effectiveness of capping 

open-ended lines is about $400/Mg VOC. The EPA believes this finding also 

applies to most open-ended lines in VC service. However, EPA investigated 

the retrofit expenditure for capping open-ended lines at the plants operated 

by Commenter IV-D-3 and found that certain open-ended lines resulting when 

multi-purpose lines used to charge materials to polymerization reactors in 

PVC plants are in VC service (i.e., charging VC) may be unreasonable to cap, 

because of the high cost associated with additional piping and other retrofit 

requirements (Docket Items IV-C-9, IV-B-10). For this reason, EPA has 

decided to exempt certain open-ended lines in batch operations from the 

requirements of Subpart V. 

The basis for the comment that compliance with Subpart V would require 

plants to retrofit their VC service pumps with seal sensors is unclear. The 

VC standard requires plants to minimize emissions from seals on pumps in VC 

service by installing sealless pumps, pumps with double mechanical seals, or 

2-27 
P.37 

equivalent. Plants choosing to meet the requirement by installing pumps with 

double mechanical seals are required to maintain the pressure between the two 

seals so that any leak that occurs is into the pump cr by ducting any VC 

between the two seals to the primary control device. In order to ascertain 

proper operation of these seal systems, some method of monitoring the barrier 

fluid is essential. To tne EPA's knowledge, area-wide monitoring is only 

effective for detecting large leaks and cannot be relied upon to indicate the 

need for repair of seal systems prior to catastrophic failure. Information 

from several PVC plants about their seal systems indicates a range of 

monitoring methods from a sight glass marking the level of fluid in the 

barrier fluid pot to a pressure gauge measuring the nitrogen pad used tc 

maintain the barrier fluid at a positive pressure to the pumped material. 

The EPA considers these types of methods of monitoring the seal system to be 

adequate for meeting the Subpart V requirements for seal sensors on pumps 

with double mechanical seals. 

Comment Approval of Existing Plans 

Three commenters (IV-D-1, IV-D-3, IV-D-4) questioned the requirements 

for obtaining approval for leak detection and elimination programs. One 

commenter (IV-D-4) recommended that resubmission of plans be required only 

if plants modify their plans. The second commenter (IV-D-1) recommended that 

already approved plans be exempt from resubmittal requirements. The commenter 

(IV-D-1) suggested that the standard specify that plans submitted for approval 

that are not acted upon within 60 days will be considered approved. 

The third commenter (IV-D-3) questioned whether effective existing leak 

detection and elimination programs would be deemed equivalent to Subpart V if 

they did not contain the extensive administrative requirements of Subpart V. 

The commenter added that past experience in submitting equivalency requests 

has indicated that significant man-hours are required to prepare an acceptable 

equivalency request. 

2-28 
P.38 

Response 

The commenters misinterpreted the meaning of the provision in proposed 

40 CFR 61.65(b)(8) which introduces criteria for approval of leak detection 

and elimination plans. The EPA does not intend for plants to resubmit plans 

already approved under the original standard. Only new or modified plans are 

required to be submitted for approval under the revised standard. EPA will 

use Subpart V, as an aid, when evaluating compliance with requirements for 

pumps, compressors and other equipment components. However, compliance with 

the VC standard requirements (in 40 CFR 61.65(b)(8)(3)) for these equipment 

components represents compliance with Subpart V. "Equivalency" of existing 

leak detection and elimination programs with the Subpart V requirements may 

be demonstrated through a performance test of valves as prescribed in proposed 

40 CFR 61.61(b)(8)(ii). This does not apply to equipment requirements for 

pumps and other equipment or the performance standard for leaks from pressure 

relief devices. 

Comment Basis of Subpart V Requirements 

The commenter (IV-D-3) stated that the emission reductions projected for 

Subpart V are based on refinery fugitive data and are not accurate for the VC 

industry which is a low-leak industry. 

Response 

Subpart V was developed based on leak studies for VOC, in general, and 

benzene, specifically. As noted by the commenter, these studies were performed 

at petroleum refineries. However, EPA investigated other leak studies performed in the synthetic organic chemical manufacturing industry (SCCMI) in 

developing equipment leak standards for SOCMI. (Vinyl chloride production is 

part of SOCMI.) The SOCMI equipment leak standard (40 CFR Part 60 Subpart 

VV) contains the same equipment and work practice requirements as Subpart V. 

The differences between petroleum refinery and SOCMI leak data were found to 

be unimportant in developing standards for these industries. 

In addition, Subpart V contains a provision for low-leak plants such as 

some of the plants in the VC industry (see 40 CFR 61.243). This provision 

2-29 
P.39 

allows plants that have demonstrated their low-leak status to monitor for 

leaks on a less frequent basis and therefore significantly reduce the cost of 

controlling equipment leaks to the required level. 

Comment ' Subpart V 2. Method 21 - Notice for Review 

The commenter (R-D-9) stated that EPA. should issue a notice allowing 

for public review and comment on Subpart V and EPA Test Method 21 as they 

aoplv to VC. 

Response 

Comments on Subpart V and EPA Test Method 21 as they apply to the VC 

standard have been considered in developing the promulgated standard for VC. 

A. separate notice is not needed. Responses to specific comments on Subpart V 

and Method 21 as they apply to VC are included in Sections 2.3.7 and 2.3.8. 

2.3.3 Alternative Compliance Demonstration Option 

Comment VOC Service vs. VC Service Components 

Four commenters (IV-D-1, IV-D-4, IV-D-8, IV-D-9) requested that the 

provision allowing plants to demonstrate equivalency of leak detection and 

elimination programs with Subpart V through a performance test specify a 

sample of VC service valves to be tested instead of VOC service valves. Two 

of the commenters (IV-D-8, IV-D-9) stated that testing of VOC service valves 

is inappropriate under a standard regulating VC. 

Response 

The EPA agrees that specifying a performance test of valves in VC 

service would be more appropriate for demonstrating the effectiveness of a 

plant's leak detection and repair program for controlling VC leaks. Subpart V 

already includes an option for plants to demonstrate their program's effectiveness through an annual performance test of VC service valves (see 

40 CFR 61.243). However, in response to concerns raised by industry representatives, EPA recognized if a performance test of VC service valves is 

2-30 
P.40 

prescribed, some plants would have to identify, tag and keep a record of all 

VC service valves for the first time. At the August 30, 1984, meeting of the 

National Air Pollution Control Techniques Advisory Committee (NAPCTAC), 

industry representatives voiced opposition to inventorying equipment components 

for purposes c' leak testing because of the additional administrative burden 

associated with tagging equipment and maintaining records. The EFA believes 

this administrative burden can be reduced without affecting the level of 

control expected to be demonstrated during the performance test by allowing 

plants to test a sample of valves in VOC service which are more readily 

icentifiab'e. The EPA's decision tc specify a performance test of VOC 

service valves is based on the assumption that if 2 percent or less of the 

tested VOC service valves are leaking, it is, reasonable to expect that 

2 percent or less of the VC service subset of these valves are leaking. 

Based on these considerations, EPA. sees no reason to revise this provision. 

Comment Leak Criteria 

Two commenters (IV-D-8, IV-D-9) recommended that the provision allowing 

plants to demonstrate equivalency of existing leak detection and elimination 

programs with Subpart V through a performance test specify that instrument 

readings exceeding the plant's approved leak definition be used as the leak 

criteria rather than instrument readings greater than 10,000 ppm as specified 

in Subpart V. The commenter stated that use of the plant-specific leak 

definition would be more consistent with the provision requiring plants to 

develop leak definitions as part of their leak detection and elimination 

programs. 

Response 

The commenter apparently believes that if a performance test is to 

demonstrate the effectiveness of existing leak detection and repair .programs 

practiced by plants relative to the Subpart V requirements, it should be 

based on the leak definition implemented as part of the existing program. In 

contrast, EPA believes that demonstration of effectiveness of existing 

programs [relative to Subpart V] can be achieved only with a performance test 

2-31 
P.41 

on valves using the leak criterion in Subpart V (i.e., instrument readings of 

greater than 10,000 ppm at the interface based on calibration with methane). 

In fact, using the Subpart V leak criterion during the performance test is 

more appropriate then using the plant-specific definitions because of differences in plant-specific leak definitions which contribute to ineffective 

programs. Use of a standard ""eak criterion ensures that the performance test 

is applied with equal stringency at all plants throughout the industry. 

Plants may request that existing leak definitions established as part cf 

their plant-specific programs be allowed for use during performance tests. 

Use of the plant-specific leak definitions will be allowed if they are 

demonstrated to be more stringent than the leak criterion found in Subpart V. 

Comment Number of Valves Required to be Tested 

Three commenters (IV-D-4, IV-D-8, IV-D-9) requested clarification 

regarding the number of valves required to be tested as part of the performance test to demonstrate equivalency of leak detection and elimination 

programs with Subpart V. 

Response 

The provision in proposed 40 CFR 61.65(b)(8)(ii)(B) prescribing the 

performance test states that "a minimum of 200 or 90 percent of the total 

valves in VOC service" within each process unit are to be tested. Specifically, process units with more than 200 valves in VOC service are required to 

test at least 200 valves while process units with less than 200 valves in VOC 

service must test 90 percent or more of valves. Accordingly, the provision 

has been clarified: 

§61.65(b)(8)(ii)(B) 

"For each performance test, a minimum of 200 or 90 percent, whichever is 

less, of the total valves . . . . " 

Comment 30 Day Retest & Annual Option 

Four commenters (IV-D-1, IV-D-3, IV-D-4, IV-D-5) suggested that plants 

failing to demonstrate equivalency of existing leak detection and elimination 

2-32 
programs with Subpart V through a performance test be allowed to retest 

within 30 days rather than become automatically subject to all Subpart V 

requirements. Commenter IV-D-3 added that a retest would provide incentive 

for plants to evaluate and correct problems prior to the retest to avoid 

becoming subject to Subpart V. Commenter IV-D-4 explained that e. retest is 

appropriate considering the time required to implement Subpart V. Two 

commenters (IV-D-1, IV-D-3) also recommended that plants be allowed the 

option of reverting back to the existing leak detection and elimination 

programs after a year under Subpart V. 

One commenter (IV-D-3) recommended dropping inclusion of Subpart V 

requirements in the VC standard, but maintaining the proposed provision 

requiring plants to demonstrate the effectiveness of their existing leak 

detection and elimination program through an annual performance test. 

Response 

The changes recommended by the commenters are not consistent with the 

purpose for adding Subpart V to the VC standard. The VC standard, as revised, 

requires plants to implement an effective leak detection and elimination 

program for valves either by complying with Subpart V or by following their 

existing program if it results in fewer than 2 percent leaking valves. As 

discussed above, other requirements of Subpart V will be used to supplement 

compliance determinations with §61.65(b)(8). In the EPA's judgement, a 

performance test measuring greater than 2 percent leaking valves is indicative 

of an inadequate existing program. Consistent with the purpose of adding 

Subpart V, it is appropriate to require these programs to be upgraded to 

comply with Subpart V requirements because they represent an effective 

program for detection and repair of leaks from valves. 

The performance test on valves is a convenient and efficient way for 

plants to demonstrate the effectiveness of their existing leak detection and 

elimination programs without the additional burden of inventorying equipment 

components and maintaining records. However, once failure of a performance 

test triggers Subpart V and the associated inventory and recordkeeping 

requirements, the benefit of the convenient and efficient performance test 

2-33 
P.43 

option no longer exists. However, under Subpart V, monitoring of valves may 

also be limited to an annual performance test as long as 2 percent cr fewer 

valves are found to leak. 

Comment Impact of Performance Test Failure 

Two commenters (IV-D-3, IV-D-4) recommended that failure by plants to 

demonstrate through a performance test that fewer than 2 percent of valves 

leak should trigger Subpart V requirements for valves only and not cfher 

equipment components. 

Response 

The commenters' concern is not relevant because plants complying with 

the equipment leak provisions of the VC standard already meet the Subpart V 

requirements for equipment components other than valves and flanges, with the 

possible exception of open-ended lines. (As discussed in Section 2.3.2, 

plants not currently complying with the open-ended line requirements in 

Subpart V will have to cap these lines. Capping of open ended lines is 

considered by EPA to be a cost-effective method for controlling leaks from 

open-ended lines.) In addition, the requirements of Subpart V will only be 

used to supplement determinations of compliance with §61.65(b). If compliance 

with Subpart V is not demonstrated by a plant, the plant does not comply with 

Subpart F. 

2.3.4 Leak Definition 

Comment Clarification of Leak Definition 

Three commenters (IV-D-4, IV-D-8, IV-D-9) requested clarification 

regarding the requirement that plants establish a leak definition as part of 

their leak detection and elimination program. Two of the commenters (IV-D-8, 

IV-D-9) recommended that the provision requiring plants to establish a leak 

definition as part of their leak detection and elimination program indicate 

whether the leak definition applies to both area monitors and to portable 

monitors, or just to area monitors. The third commenter (IV-D-4) recommended 

modifying the provision requiring establishment of a leak definition to 

2-34 
require plants instead to define a leak level in conjunction with area 

monitors such that area monitor readings in excess of the defined level are 

not considered leaks in themselves but rather an indication to search for a 

"leak" as now defined by the criteria of Subpart V. 

Response 

Under the original VC standard, plants are required to define a leak as 

part of their program for detecting and eliminating equipment leaks. Although 

different approaches were taken by plants, the intent was for plants tc 

establish a definition of leak as measured by an area monitor compared to 

•background concentrations. Then, when portable monitors were used to pinpoint leak sources, a different leak definition was to be applied. Because 

of differences among plants in the number and location of area monitors and 

background concentrations, leak definitions pertaining to area monitor 

detections necessarily vary and should remain a plant-specific measurement. 

However, both the industry and EPA may want to review and alter the area 

monitor leak definitions to improve their usefulness. 

Unlike the leak definition for area monitors, the definition used to 

measure leaks from specific equipment components can and should be standardized. Addition of Subpart V to the VC standard provides this standardization. As a result, plants no longer are required to develop their own leak 

definition for detecting leaks with a portable monitor. 

In response to the comment that leaks defined in conjunction with area 

monitor detection of leaks should be considered an action level indicating 

the need to search for a leak, it should be pointed out that a reading in 

excess of the area monitor leak definition is an indication of a leak. Even 

if the actual source of the leak is not found, the event is recorded as a 

leak for compliance purposes. 

2.3.5 Relief Valve Monitoring Requirements 

Comment Rupture Disc Exemption 

Three commenters (IV-D-3, IV-D-8, IV-D-9) requested that relief valves 

equipped with rupture discs be exempt from the proposed monitoring requirements 

?-?C 
P.45 

for relief valves. Commenter IV-D-9 further recommended that relief valves 

connected to a process line, recovery system or equivalent be exempt from 

relief valve monitoring requirements. The commenters recommended that 

Subpart V be revised accordingly. 

Response 

Section 112 of the Clean Air Act requires EPA to set performance 

standards, whenever feasible. In the case of relief valve leaks, it is 

possible and appropriate for a performance standard to be applied. Furthermore, the EPA does net agree that only equipping relief valves with rupture 

.discs is adequate basis for exempting relief valves from monitoring requirements for leaks. As part of good operation and maintenance practices, 

rupture discs should be checked at least annually and after each discharge to 

maintain their integrity. The best way to ensure that integrity of the 

rupture disc is constantly maintained is through the performance test in 

Subpart V. 

The EPA agrees that venting a relief valve through a closed vent system 

to a control device warrants exemption from monitoring requirements. The 

Subpart V requirements referenced in the VC standard for controlling equipment leaks from relief valves already exempt, relief valves connected through 

a closed vent system to a control device from monitoring requirements. In 

this situation, process lines or recovery systems may qualify as control 

devices for the purpose of complying with Subpart V. 

2.3.6 Calibration Requirements 

Comment Calibration Gas for Monitors 

Two commenters (IV-D-8, IV-D-9) requested clarification on calibration 

gas requirements for monitors under the revised standard. Commenter IV-D-9 

recommended that.the standard specify continued use of VC as calibration gas 

instead of methane or hexane as prescribed in Subpart V. 

2-36 
P.46 

Response 

There are two different definitions of a leak, and thus two different 

calibration gas requirements. Leaks are detected in two different ways: by 

an area monitor specific to VC measuring the general condition or possible 

presence of VC leaks in an area; and by routine leak detection monitoring 'of 

particular valve or pump seals, etc.) to determine if specific pieces of 

equipment are leaking. 

The area monitor must be specific to and calibrated with VC because 

other organics may be present in the air to such an extent that the VC 

concentration would be masked. Whether the routine leak detection monitor is 

calibrated with VC or some other organic is not as critical to EPA as long as 

that monitor is less responsive to VC than the alternative calibration gas. 

If such a monitor is calibrated with VC, then the definition of a leak is in 

effect lowered, and EPA would consider that acceptable in an alternative 

method request. 

Comment Monitor Span Checks 

Two commenters (IV-D-8, IV-D-9) suggested that because the same 

instruments are often used for both area monitoring and exhaust gas monitoring, a single span check using a 10 ppm VC standard should be allowed 

instead of two separate span checks. 

Response 

Area monitoring and exhaust gas monitoring serve two different regulatory 

purposes within the standard. While a 10 ppm span is appropriate for emission 

monitoring for the exhaust gas standard, it may or may not be appropriate for 

area monitoring, depending on the background concentration of VC in the areas 

of the plant to be monitored. Therefore, while the same instrument may be 

used to serve both monitoring requirements, there is no regulatory justification for requiring that the required span gases be the same concentration. 

2-37 
P.47 

2.3.7 Subpart V 

Comment Exemption from Administrative Requirements 

Two commenters (IV-D-8, IV-D-9) requested that a provision be added to 

Subpart V allowing exemption from certain inventory and recordkeeping requirements for valves if a performance test indicates that 2 percent cr -ewer 

valves in VHAP service are leaking. Commenter IV-D-8 also recommended that a 

similar provision be added to Subpart VV. 

Response 

Subpart V of Part 61 and Subpart VV of Part 60 already contain a prcvis":oi' 

which allows plants that establish a low valve leak rate (i.e., less than 

2 percent) to skip monthly monitoring and to perform monitoring on an annual 

basis. This differs from the provision in the VC standard that exempts 

plants that initially, annually, and at the request of EPA, demonstrate a 

2 percent or better leak rate from certain inventory and recordkeeping 

requirements. Exempting VC plants that consistently demonstrate a low leak 

rate from these inventory and recordkeeping requirements is reasonable 

because these plants have over eight years of operating experience under 

formal leak detection and repair plans required by the original VC standard. 

Special consideration should be given to those plants for their successful 

efforts in response to the original VC standard requirements. Because other 

plants subject to 40 CFR Part 61 Subpart V and 40 CFR Part 60 Subpart VV do 

not have this level of experience nor have they been subject to a prior NSPS 

or NESHAP for equipment leaks, it is reasonable to require these plants to 

comply with all the requirements under Subpart V. 

Comment Equipment Identification 

The commenter (IV-D-8) recommended that Subpart V be revised to also 

allow identification of equipment by labeling on engineering drawings rather 

than only tagging in the field. 

•38 
P.48 

Response 

Methods other than tagging in the field are currently allowed for 

identification of equipment components for testing purposes. However, more 

detail than is typically available on engineering drawings is often required. 

For example, photographs of equipment components or other identification aids 

may be necessary to ensure that inspectors and plant personnel are able to 

find the location of all equipment components subject to Subpart V 

requirements. 

Comment Flange Identification 

The commenter (IV-D-8) stated that Subpart V should, clearly specify that 

only flanges which have been found to be leaking are required to be identified. 

He noted the difficulty and expense in identifying every flange because many 

are covered with insulation. 

Response 

Flanges need to be identified to ensure effectiveness of the leak 

detection and repair requirements of Subpart V. However, EPA recognizes that 

identification of covered flanges and other connectors according to the 

inventory requirements in Subpart V could be too costly. Thus, in response 

to this comment, EPA has decided to add a provision to Subpart V allowing 

plants to forego identification of covered flanges. In addition, Subpart V 

is being revised to exempt all other connectors from identification and 

tagging requirements. However, these connectors are still subject tc leak 

detection and repair requirements. 

Comment Valve Repair 

The commenter (IV-D-8) stated that valves which have undergone repair 

during a shutdown and which are found to still be leaking after startup 

should be considered a new leak and not an extension of the first leak, 

providing proper repair techniques were applied. The commenter explained 

that the success of the repair often can be tested only under operating 

conditions. 

2-39 
P.49 

Response 

The commenter's recommended approach is already allowed. In these 

cases, a review of the repair efforts is made by EPA. If they are judged to 

be proper, then the subsequent leak would be a new leak. 

Comment Process Accumulators 

The commenter (IV-D-3) requested that the Subpart V provision regulating 

process accumulators be modified fo specify that vents and not all fugitive 

sources on process accumulators in VHAP service are required to be controlled. 

Response 

The process accumulator vent standard in Subpart V is not applicable to 

PVC and EDC/VC plants because these vents are. already regulated under the VC 

standard by the more restrictive requirements of the exhaust gas limits. 

However, valves and other equipment components associated with process 

accumulators in VHAP service are intended to be controlled like other-VHAP 

service equipment components under Subpart V, and consequently, under the VC 

standard. 

Comment Connector Definition 

Two commenters (IV-D-8, IV-D-9) stated that the definition of connector 

in Subpart V as it applies to VC should clearly exempt welded joints which 

are permanent. 

Response 

Subpart V already contains the recommended exemption. 

2.3.8 Method 21 

Comment Sample Flowrate 

Two commenters (IV-D-8, IV-D-9) pointed out that the nominal sample 

flowrate requirement of one-half to 3 liters per minute in EPA Test Method 21 

should be deleted because a response time equal to or less than 30 seconds is 

specified in a separate provision. The commenters explained that certain . 

reliable instruments are precluded by the flowrate requirements. 

2-40 
P.50 

Response 

Method 21 includes a flowrate specification specifically to exclude from 

the method those types of monitors that have a large or unccnfined sample 

inlet area, because EPA found that those instruments were not sufficiently 

responsive to leaks of a magnitude that EPA expects to be identified ano 

corrected. 

Comment Probe Placement 

Two commenters (IV-D-8, IV-D-9) requested that EPA Test Method 21 be 

revised to specify that equipment components are to be monitored by placing 

the probe inlet within 1 cm of the component interface rather than directly 

on the surface of the interface. 

Response 

Method 21 for measuring VOC leaks from fugitive emission sources specifies 

that the portable monitor is to be placed on the surface of the interface to 

be tested. In the case of rotating equipment such as pumps, a distance of 

1 cm between the probe inlet and equipment interface is specified. The leak 

definition specified in conjunction with Method 21 is based on data collected 

by placing the sample probe directly on the surface of the interface (except 

for rotating shafts on pumps and compressors). In the EPA's judgment, changing 

the sampling distance to 1 cm for all equipment components is inappropriate. 

2.4 DEFINITI0NS 

2.4.1 In VC Service 

Comment Reason for Revising "In VC Service" Definition 

Three commenters (IV-D-1, IV-D-4, IV-D-14) recommended modification to 

the revised definition of "in VC service" and to the related provision in 

proposed 40 CFR 61.67(h) which describes how to determine whether equipment 

is in VC service. One of the commenters (IV-D-14) stated that the rationale 

for changing the definition of "in VC service" and adding requirements for 

determining whether equipment is in VC service has not been adequately 

2-41 
P.51 

explained and that the existing definition should be retained because it is 

clear and workable. The commenter (IV-D-14) also pointed out that certain 

pieces of equipment alternate in and out of VC service, depending on the 

operation being conducted. 

Resoonse 

During the review of enforcement and compliance experience under the VC 

standard, EPA found that the classification of "in VC service" is a point of 

contention between regional compliance and industry personnel (Docket Item 

II-A-19). The EPA concluded that the definition of "in VC service" needed 

clarification tc ensure that all equipment capable of emitting VC is identified and that the burden of identification falls on plant personnel and not 

Regional compliance personne"1. To achieve the desired clarification, EPA 

adopted the approach for identifying equipment in VHAP service developed for 

the Subpart V regulation for equipment leaks. In Subpart V, a definition for 

"in VHAP service" is given along with a method for determining whether 

equipment is in VHAP service. The VHAP provisions effectively place the 

burden on plant personnel to identify all equipment capable of emitting VHAP. 

The EPA believes that adoption of the "in VHAP service" provisions of Subpart V 

in the VC standard is reasonable and appropriate and that changes to these 

provisions in context of the VC standard are not warranted. 

The concern raised by the commenter regarding equipment that alternates 

in and out cf VC service is apparently directed toward polymerization reactors 

and other vessels and equipment that normally contain VC but are occasionally 

purged prior to opening for routine or emergency maintenance. The VC standard 

contains specific requirements for minimizing emissions during reactor and 

equipment opening. Discharges from equipment not in VC service do not 

contain VC and therefore are not intended to be regulated by the standard. 

The provision regulating relief valve discharges has been clarified to apply 

to discharges containing VC to the atmosphere from relief valves on equipment 

in VC service. The provision has also been clarified to more adequately 

address equipment used in batch processes by referring to contained volumes 

in addition to process fluid streams. 

2-42 
P.52 

2.4.2 EDC and VC Purification 

Comment Clarification of Covered Equipment 

Five commenters (IV-D-1, IV-D-3, IV-D-4, IV-D-5, IV-D-14) requested 

clarification of equipment covered by the revised definition of EDC purification,- particularly storage tanks. Commenter IV-D-14 requested confirmation 

that equipment listed in a previous draft of the definition but deleted in 

the proposed definition are not intended to be covered. These equipment 

included storage tanks for crude EDC; light ends separation, condensation and 

storage; heavy ends separation, condensation and storage; inprocess EDC 

storage; and dryers. Commenter IV-D-5 questioned the claim in the preamble 

that all equipment following EDC formation was intended to be covered by the 

standard, noting that this intent is not expressed in the preamble to the 

original standard. Two of the commenters (IV-D-1, IV-D-14) requested that 

EPA provide justification for any additional equipment included in the 

revised definition. Commenter IV-D-4 also requested clarification of whether 

storage vessels are included under the revised definition of "VC purification." 

Three commenters (IV-D-1, IV-D-5, IV-D-14) stated that regulation of 

storage tanks is not justified because of high cost and low emission reduction. 

Commenters IV-D-1 and IV-D-5 referred to information submitted previously to 

EPA providing cost and emission reduction estimates for regulating storage 

tanks (Docket Item II-E-73). Commenter IV-D-5 stated that EDC storage tanks 

are already well controlled, have low VC emissions and thus have low health 

risks in comparison with other sources covered by the standard. He pointed 

out that the same basis was used to conclude that regulation of other VC 

sources not previously covered by the standard is not warranted. 

One additional commenter (IV-D-7) recommended alternative language for 

the definitions of EDC purification and VC purification to better clarify 

specific equipment components subject to the standard. 

Response 

The original VC standard did not clearly delineate which purification 

process equipment were subject to regulation as EDC and VC purification 

equipment. However, it is clear from the background information developed 

2-43 
P.53 

for the original standard that purification equipment containing VC were 

intended to be covered by the standard. During the review of the standard, 

EPA learned that different interpretations of the definitions of EDC and VC 

purification had been applied by industry personnel with the result that some 

plants were controlling emissions from all equipment in the purification 

processes, including storage tanks while others were controlling only the 

major emission sources (i.e., finishing columns). Interpretation cf these 

definitions also varied among compliance personnel. In particular, compliance 

personnel were concerned that some plants interpreted the definition of VC 

purification such that ccntrol of emissions from VC storage following VC 

.purification was not required. As a result of these findings, EPA believed 

it was appropriate to clarify the definitions of EDC and VC purification in 

the proposed revisions to the standard, primarily to ensure elimination of 

overly restrictive interpretations of the definitions resulting in failure to 

control potentially significant sources of VC emissions such as VC storage 

tanks. 

Comments received on the proposed definitions addressed the 

appropriateness of including EDC storage tanks under the revised definition 

of EDC purification equipment. Because these tanks represent a much smaller 

potential source of VC emissions than VC storage tanks and because the intent 

of the original standard is unclear, EPA decided to evaluate the reasonableness 

of regulating EDC storage tanks under the VC standard. For this evaluation, 

EPA estimated the costs and VC emissions reductions that would result from 

regulation of EDC intermediate and final storage tanks which follow the final 

finishing column. Based on emissions data submitted by the commenters, 

uncontrolled VC emissions from intermediate and final EDC storage tanks at a 

typical EDC/VC plant were estimated to be 0.1 to 2 Mg/yr VC. Control costs 

were based on venting existing EDC storage tanks to an existing primary 

control device (i.e., incinerator) as required by the standard for purification 

equipment. The EPA estimated the cost to control these tanks would exceed 

$8,500/Mg VC (1984 dollars) and achieve an emission reduction of 0.67 to 

14 Mg/yr (Docket Item IV-E-8). The EPA concluded from their evaluation that 

control of VC emissions from EDC storage tanks which store EDC after the 

2-44 
P.54 

final finishing column is not cost effective and that regulation of these 

tanks under the VC standard is not warranted. 

Although the standard under review regulates VC emissions, EPA considered 

the benefit of controlling other VOC, primarily EDC, in its decision regarding 

whether to regulate these tanks uncer the VC standard. Many o~~ these tankj, 

•are already controlled for VOC (and thus VC) according to state SIP provision;. 

The remainder of these tanks are located primarily in attainment areas where 

less stringent VOC regulations apply. Moreover, EPA is currently investigating 

EDC emissions for possible regulatory development as a hazardous air pollutant 

under Section 112. The'potential emission reduction associated with ccntro" 

.of EDC storage tanks would amount to about 600 Mg/yr and the resulting cost 

effectiveness would be about $330/Mg EDC (Docket Item IV-B-8). Intermediate 

and final EDC storage tanks which follow the final finishing column would 

likely be regulated under an EDC regulation. The EPA concluded that regulation 

of these storage tanks would be more appropriately carried out by these other 

regulatory mechanisms. 

2.4.3 Relief Valve 

Comment Exemption of Nonventing Pressure Control 

Systems 

Four commenters (IV-D-1, IV-D-4, IV-D-9, IV-D-14) requested additional 

clarification to the definition of relief valve. Two of the commenters 

(IV-D-1, IV-D-9) requested that relief valve be defined as any pressure 

relief system used to protect process components from overpressure conditions 

by venting directly to the atmosphere. The commenters further recommended 

that the definition of relief valve explicitly exempt pressure control 

systems such as reaction shortstop systems, refrigerated water systems and 

other systems which act to reduce pressure by means other than venting to the 

atmosphere. The third commenter (IV-D-4) stated his understanding from past 

discussions with EPA that the nonventing pressure control systems are not 

intended to be covered by the definition. The commenter (IV-D-4) also 

recommended that the definition be modified to exclude all devices controlling 

flow around an incinerator, not just control valves. The fourth commenter 

•45 
(IV-D-14) stated that although the revised relief valve discharge standard 

eliminates the most significant problem in the original regulation, additional 

clarification to the definition cf relief valve in proposed 40 CFR 61.61(v) 

is needed to adequately reflect the expressed intent in the preamble 

•'50 FP. 1192). The commenter recommended that the definition specifically 

identify all types of relief devices that are subject to regulation as i i'Xxr 

valves. This clarification would eliminate vagueness and achieve consistency 

with the preamble. 

Response 

One purpose of defining relief valve is to aid in identification of 

emissions of VC to the atmosphere which are subject to the relief valve 

discharge standard. The commenters' concern that the definition of relief 

valve could be interpreted to include shortstop systems and refrigerated 

water systems is irrelevant because it is difficult to conceive that VC could 

be emitted from these pressure control systems to the atmosphere. Nonetheless, 

EPA has revised the definition of relief valve to explicitly exclude shortstop 

systems and refrigerated water systems. However, the promulgated definition 

has not been revised to exempt all pressure control systems that protect 

process components from overpressure conditions by methods other than venting 

directly to the atmosphere. The EPA believes that exemption of all nonventing 

pressure control systems would be inconsistent with the intent that discharges 

from gasholders or other containment systems to which relief valve discharges 

may be vented are subject to the relief valve discharge standard. 

The definition of relief valve has also been revised as recommended to 

exclude all devices controlling flow around an incinerator, and not just 

control valves. These pressure control devices act to bypass exhaust gas 

around the incinerator in the event of overpressure conditions or incinerator 

malfunction. Bypassed exhaust gas is subject to the 10 ppm exhaust gas 

standard and not to the limits for relief valve discharges unless the bypass 

is caused by a relief valve discharge. 

Finally, the definition identifies several types of pressure relief 

devices which are to be considered "relief valves" when evaluating compliance 

2-46 
P.56 

with the relief valve discharge standard. As explained in the preamble to 

the proposed revisions (50 FR 1187), this definition is necessary to clarify 

that the relief valve discharge standard applies not only to emissions from 

pressure relief valves but to other types of pressure relief devices as well. 

In addition to the listed equipment, the definition also states that any 

other pressure relief systems that function in the same way (i.e., to protect 

process components from overpressure conditions) are to be considered relief 

valves. In this way, the intent that all pressure renief devices, and not 

just certain types, are subject to the relief valve discharge standard is 

emphasized. 

Comment "Relief Valve" vs. "Relief Device" 

Two commenters (IV-D-8, IV-D-9) suggested that the term "relief valve" 

be changed to "relief device" to be consistent with the American Society of 

Mechanical Engineers (ASME) designation and common usage and to avoid the 

confusion of referring to a rupture disc as a valve. 

Response 

The commenter is correct in noting that "relief valve" is a more narrow 

term than "relief device" and that "relief device" better connotes the 

variety of pressure relief equipment subject to the VC standard. However, 

most pressure relief discharges from equipment in PVC and EDC/VC plants occur 

through relief valves. As a result, the original standard was written in 

terms of "relief valve" for convenience even though other relief devices were 

intended to be included. In order to clarify that all pressure relief 

devices are subject to the relief valve discharge standard, a definition of 

relief valve has been added. The EPA believes that the added definition 

provides a less cumbersome solution for clarifying equipment subject to the 

standard than the commenter's suggestion. Nonetheless, EPA appreciates the 

confirmation by the industry commenter indicating understanding of the broad 

use of the term "relief valve". 

•47 
P.57 

2.4.4 Leak 

Comment "Leak" Definition 

One commenter (IV-D-14) recommended that the definition of leak be 

revised to distinguish what a leak is from events that suggest the presence 

of a leak. 

Response 

As discussed in the preamble to the proposed revisions (50 FR 1192), one 

purpose of adding a definition of leak to the VC standard is to help distinguish. VC emissions resulting from "leaks" from VC emissions occurring as 

.relief valve discharges and exhaust gas. To achieve this purpose, the 

definition of leak lists events regulated by the VC standard and Subpart V 

(incorporated in the VC standard by reference) which indicate a need for 

repair or further action on the part of plant owners or operators. As 

explained in responses to other comments, EPA believes that each of the 

regulated events listed in the definition represent adequate" criteria for 

requiring repair or further action and are appropriately included in the 

definition. 

Comment Indications of Liquid Dripping 

Six commenters (IV-D-1, IV-D-2, IV-D-3, IV-D-4, IV-D-8, IV-D-9) 

recommended modifications to the portion of the leak definition pertaining tc 

indications of liquid dripping. Four of the commenters (IV-D-1, IV-D-3, 

IV-D-8, IV-D-9) stated that indications of liquid dripping should be considered 

leaks only if confirmed by an objective measurement. Commenter IV-D-3 

suggested that an instrument reading greater than 10,000 ppm be the criterion 

for establishing that dripping liquids are VC leaks. Commenters IV-D-8 and 

IV-D-9 recommended that barrier fluid levels and/or pressures be relied upon 

instead as indicators of VC leaks from double mechanical seal pumps. Commenter 

IV-D-4 suggested that leaks defined as indications of liquid dripping should 

be limited to liquid dripping from pump seals in VC service. Commenter 

IV-D-2 recommended deletion of indications of liquid dripping from the leak 

definition on the basis that drips from pumps are likely not VC. 

2-48 
P.58 

Response 

The EPA believes that indications of liquid dripping is appropriate 

criterion for requiring repair actions on double mechanical seal pumps in VC 

service and should therefore be included in the definition of leak. Visible 

leakage from all types of pump sea's, including double mechanical seals 

required by the VC standard, is generally indicative of seal wear even if nc 

VC is present in the leaking fluid. To prevent further seal wear resulting 

in catastrophic seal failure accompanied by VC emissions to the atmosphere, 

the seals should be repaired soon after leakage is initially detected. The 

same leak criterion for double mechanical seal pumps is prescribed in ecuiomer.' 

leak standards for SOCMI and benzene. In the VC standard, the portion of the 

leak definition referring to indications of liquid dripping applies only to 

pumps in VC service. 

Barrier fluid level and pressure sensors also provide indication of 

certain types of seal wear and are thus included in the Subpart V requirements for detecting leaks from double mechanical seal pumps. In the EPA's 

judgment, monitoring of barrier fluid as well as dripping liquids is necessary 

to ensure control of equipment leaks from pumps with double mechanical seals. 

Comment Sensor Detection of Seal Failure 

Three commenters (IV-D-1, IV-D-2, IV-D-4) disagreed with inclusion of 

"sensor detection of failure of a seal system" in the definition of leak. 

Two of the commenters (IV-D-1, IV-D-2) explained that seal system failures 

are not necessarily indicative of VC leaks to the atmosphere. The third 

commenter (IV-D-4) stated that sensor detection of seal failures should be 

deleted from the definition of leak in conjunction with the recommended 

removal of proposed seal monitor requirements for pump seals. 

Response 

As in the case of indications of liquid dripping, EPA believes that 

sensor detections of seal failure (i.e., detection of a rapid change in 

barrier fluid level or pressure) is appropriate criterion for requiring 

repair actions for double mechanical seal pumps in VC service and should be 

2-49 
P.59 

included in the definition of leak. Although failure of an inner seal on a 

double mechanical seal pump in VC service may not result in direct emission 

of VC to the atmosphere, continued operation would result in total seal 

failure accompanied by direct emission of VC to the atmosphere. The equipment 

"leak standards for 3CCMI and benzene also list sensor detection of seal 

failure as a criterion requiring repair actions for double mechanical seal 

pumps. 

The EPA is net exempting double mechanical seal pumps in VC service from 

seal monitoring requirements in Subpart V. The basis for this decision is 

described in Section 2.3.2. 

Comment Leak Definitions Under Existing Standard 

Five commenters (IV-D-1, IV-D-3, IV-D-4, IV-D-8, IV-D-9) requested 

clarification of the status of leak definitions established under existing 

leak detection and elimination programs. Commenter IV-D-1 recommended that 

leaks defined under existing approved leak detection and elimination programs 

be included in the definition of leak. Commenter IV-D-3 disagreed that 

existing leak definitions should be retained under the revised leak definition 

on the basis that some plant's existing leak definitions are much lower than 

the proposed leak definition and that imposition of Subpart V repair and 

recordkeeping requirements for leaks found under these existing, more stringent 

definitions would not be justified. Another commenter (IV-D-4) stated that 

the definition of leak should not include events regulated in the original VC 

standard of detection of ambient concentrations in excess of background 

concentration. Instead, these events should be considered an action level 

triggering a search to detect leaks on the basis of other defined leak 

criteria. Two additional commenters (IV-D-8, IV-D-9) recommended that the 

portion of the definition of leak referring to events regulated under existing 

plant programs should specifically reference the provision in the existing 

standard where these leak events are defined. 

2-50 
P.60 

Response 

Under 40 CFR 61.65(b)(8)(vi) of the VC standard, plants are required to 

establish a leak definition at an acceptable level when compared to the 

background concentration. The provision allows for different leak definitions 

to be established in different parts of the plant because of variations in 

background concentrations. The provision also allows for adjustments in leak 

definitions over time as background concentrations are reduced. During the 

review of the standard, EPA found that leak definitions established under 

this provision varied widely from plant to plant (Docket Item II-A-19). 

Differences in leak definitions used for detecting leaks with area monitors 

are in part due to the variability among plants in the number and location of 

area monitors and differences in background concentrations. Because of these 

factors, it is impossible to establish a standard leak definition applicable 

to area monitors. 

In the case of detection of leaks using portable monitors, however, it 

is possible and appropriate to establish a standard leak definition and 

method for detection of leaks. Consequently, the definition of leak in the 

VC standard includes specific criteria to be used by plants in place of 

existing definitions for identifying leaks with portable monitors. The 

prescribed leak criteria is consistent with the criteria developed for 

detection of leaks with a portable monitor under equipment leak standards for 

benzene and SOCMI and may be more or less stringent than the definitions 

established under the original VC standard. The EPA believes that the leak 

criteria developed for these other standards represent an effective program 

for detection of leaks with portable monitors and that more stringent 

definitions are not needed. 

Because of the difficulty in establishing standard criteria for 

identifying leaks with area monitors, the definition of leak incorporates the 

plant's existing definition developed for use with the plant's area monitors. 

In reviewing the standard EPA did not identify specific problems with the 

definitions of leak pertaining to area-wide monitoring systems in use by the 

plants. The EPA concluded that the area-wide leak definitions can appropriately serve their purpose. Further, EPA does not intend for changes in 

2-51 
P.61 

the standard to interfere with this method of controlling leaks. However, as 

discussed in the preamble to the proposed revisions (50 FR 1190), plants have 

the option of altering the number of points that are monitored and the 

distribution of monitoring locations associated with existing fixed-point 

monitoring plans to better complement the newly prescribed portable monitoring 

requirements. The revised portable monitoring leak detection requirements in 

conjunction with the fixed-point monitoring requirements will ensure control 

of VC emissions from equipment leaks to the level intended by the original 

regulation. 

Comment Reference to Events and Emissions 

Regulated Elsewhere 

One commenter (IV-D-14) stated that reference to events regulated under 

Subpart V and under the original leak detection and elimination requirements 

in 40 CFR 61.65(b)(8)(i) of the VC standard is not appropriate in the proposed 

leak definition because the referenced regulations do not contain leak 

definitions. The commenter (IV-D-14) further stated that the provision in 

the proposed leak definition that defines leaks as emissions not specifically 

regulated elsewhere in the standard should be omitted because it has no 

apparent basis and would be confusing. 

Response 

For purposes of the VC standard, a leak is defined as those events 

regulated under the VC standard and Subpart V (included in the VC standard by 

reference) which indicate the need for repair or further action by the plant. 

The definition of leak appropriately references where these events are 

regulated (i.e., either Subpart V or the VC standard). The provision in the 

definition that leaks include emissions not regulated under certain prescribed 

parts of the VC standard was included primarily to help ensure regulation of 

VC emissions from sources not addressed elsewhere in the standard. For 

example, although uncommon, emissions of VC occasionally occur from sources 

such as broken pipes or headers. In the past, it was unclear to some plant 

owners and operators whether these types of emissions were subject to 

2-52 
P.62 

regulation as exhaust gas, as a leak, as both, or as neither. The proposed 

definitions of leak and exhaust gas included provisions intended to clearly 

distinguish between the two types of emissions. However, these provisions 

were not intended tc imply that compliance with requirements for leaks and 

exhaust gas would be mutually exclusive. After reviewing the proposed 

definitions, it is the EPA's opinion that automatic classification of emissions 

from unconventional sources such as broken pipes as either a leak or exhaust 

gas is neither practical nor appropriate. Accordingly, the provision in the . 

definition of leak which specifies that emissions not regulated under the 

prescribed parts of the standard are to be considered leaks has been deleted. 

Comment Instrument Readings of 500 ppm Above 

Background 

Five commenters (IV-D-1, IV-D-2, IV-D-3, IV-D-4, IV-D-9) suggested that 

the distinction between leaks defined as instrument readings greater than 

10,000 ppm and leaks defined as instrument readings of 500 ppm above background 

be clarified by specifying that instrument readings of 500 ppm above background 

apply only to certain equipment. Three of the commenters (IV-D-1, IV-D-2, 

IV-D-9) recommended that instrument readings of 500 ppm above background be 

applied to relief valves when not relieving and sealless pumps. A fourth 

commenter (IV-D-3) recommended applying the 500 ppm' above background definition 

to leaks from sealless valves in addition to pumps and relief valves and the 

fifth commenter (IV-D-4) recommended applying the 500 ppm above background 

definition to non-relieving relief valves only. 

Response 

The commenters correctly pointed out that leaks defined as instrument 

readings of 500 ppm above background are intended to apply to equipment 

designated to comply with no detectable emissions. According to the revised 

VC standard, relief valves are to be operated with no detectable emissions. 

In addition, valves, sealless pumps and compressors can be designated for no 

detectable emissions under Subpart V under certain conditions. To clarify 

2-53 
P.63 

the leak definition, it has been revised to clearly distinguish between leaks 

defined as instrument readings cf 10,000 ppm and leaks defined as instrument 

readings of 500 ppm above background as follows: 

r

361.61(w) "Leak" means ar.y of several events .. . (4) detectable emissions 

as indicated by an instrument reading of greater than SCO com above 

background for equipment designated for no detectable emissions. 

Comment Reference to EPA Test Method 21 

Two commenters (IV-D-1, IV-D-4) pointed out that leaks defined as 

instrument readings of greater that 10,000 ppm should be referenced to EPA 

Test Method 21. One of the commenters (IV-D-4) also suggested that leaks 

defined as instrument readings greater the 500 ppm above background be 

referenced to Method 21. 

Response 

As recommended, the leak definition has been revised to appropriately 

reference EPA Test Method 21 as follows: 

§61.65(w) "Leak" means any of several events .. . (1) an instrument reading 

of 10,000 ppm measured according to Test Method 21 (see Appendix A of 40 CFR 

Part 60) .. . (4) detectable emissions as indicated by an instrument reading 

of greater than 500 ppm above background for equipment designated for no 

detectable emissions measured according to Test Method 21 (see Appendix A. cf 

40 CFR Part 60) . . . 

2.4.5 Exhaust Gas 

Comment Reconsideration of "Leak" and 

"Exhaust Gas" Definitions 

The commenter (IV-D-7) stated that unintentional emissions from equipment 

components for which emission limits are prescribed should not be considered 

exhaust gas, as proposed, but rather be considered as a leak, and requested 

that the proposed definitions for leak and exhaust gas be changed accordingly. 

2-54 
Response 

The EPA agrees with the commenter that in certain situations, 

"unintentional" emissions from equipment components for which emission limits 

are prescribed may be more appropriately regulated under standards applying 

to equipment leaks than standards for exhaust gas. For example, a break in 

an exhaust gas header to a control device resulting in emissions of VC to "the 

atmosphere in excess of 10 ppm would apparently be subject to the 10 ppm 

standard fcr exhaust gas under the proposed definition of exhaust gas. ?ut 

emissions from a broken header are likely to be detected by the area monitor 

and repaired in a similar fashion to leaks from specific equipment components 

such as valves and pumps. The facts of the situation, such as the reason for 

the emission, its magnitude, and the actions taken to alleviate its impacts, 

would be taken into account when determining the applicability of the standard 

to a specific incident. 

Comment Reference to Limits for Equipment 

The commenter (IV-D-14) stated that reference in the exhaust gas 

definition to ".. . equipment for which 10 ppm emission limits are prescribed" is misleading and should be deleted because the cited sections apply 

limits to exhaust gas and not equipment. 

Response 

As pointed out by the commenter, the definition of exhaust gas refers to 

several sections in the VC standard which prescribe emission limits for 

exhaust gas from various equipment in PVC and EDC/VC plants. In order to 

clarify any misunderstanding regarding which emissions are subject to regulation as exhaust gas, the definition has been revised as follows: 

§61.61(x) "Exhaust gas" means any offgas .. . in direct contact with.the 

equipment, for which emission limits are prescribed in . . . 

Comment Reference to Disposition of Exhaust Gas 

The commenter (IV-D-14) recommended that the definition of exhaust gas 

be revised to omit the words "directly or ultimately" because they do no 

contribute to the meaning of the definition. 
Response 

The definition cf exhaust gas intentionally specifies offgas discharged 

"directly or ultimately" to the atmosphere to clearly indicate that the 

disposition of the offgas does not affect the applicability of the "exhaust 

gas" standards. Whether the offgas is vented to the atmosphere, vented to a 

control device or combined with other offgas streams it is subject to the 

"exhaust gas" standards. The EPA believes the words "directly or ultimately" 

contribute meaning and should be retained. 

Comment Alternative Language

 Deoomir,endec 

The commenter (IV-D-14) recommended that the definition of exhaust gas 

recognize that all emissions which have been treated in a control device 

become exhaust gas, regardless of their origin. He recommended alternative 

language to identify exhaust gas as the object of control to 10 ppm. 

Response 

One purpose of adding a definition of exhaust gas to the VC standard is 

to help distinguish VC emissions occurring with exhaust gas from VC emissions 

resulting from leaks and relief valve discharges. The EPA believes that the 

proposed definition better achieves that purpose. Thus, the commenter's 

suggestion is rejected. 

2.4.6 Relief Valve Discharge 

Comment "Relief Valve Discharge" Definition 

The commenter (IV-D-7) recommended an alternative definition for relief 

valve discharge to replace the proposed definition. 

Response 

The commenter's recommendation that the definition of relief valve 

discharge be expanded to any "non-leak discharge" through a pressure relief 

device designated to protect process components from overpressure conditions 

is unnecessary. The definition of relief valve discharge adequately serves 

the purpose of distinguishing relief valve discharge emissions from VC 

2-56 
P.66 

emissions occurring with exhaust gas and leaks. Moreover, the definition of 

relief valve specifies that relief valves are pressure relief devices designed 

to protect process components from overpressure conditions. Inclusion of 

this description of relief valve in the definition of relief valve discharge 

is redundant and unnecessary. 

2.4.7 3-Hour Period 

Comment Potential for Three 3-Hour Exceedences 

of 10 ppm Limit 

Five commenters (IV-D-1, IV-D-2, IV-D-4, IV-D-6, IV-D-14) noted that the 

definition Qf 3-hour period creates 24 3-hour periods per day with the result 

that a single hourly average in excess of 10 ppm could cause three 3-hour 

exceedences of the 10 ppm limit. Two of the commenters (IV-D-1, IV-D-4) 

explained that establishment of rolling 3-hour averaging periods effectively 

negates the intended clarification that 1-hour averages are not the intended 

compliance criteria. Another commenter (IV-D-14) pointed out that only eight 

performance tests prescribed under 40 CFR 61.67 could be performed during a 

24-hour period. The commenters recommended that the 10 ppm regulations 

specify that a single hourly average in excess of 10 ppm can not cause more 

than one 3-hour period to be considered in excess of 10 ppm. 

Response 

The commenters correctly interpreted that the definition of 3-hour 

period creates 24 3-hour averages per day. In addition, the commenters 

correctly concluded that in cases when the control device fails significantly 

causing a 1-hour exceedance of the 10 ppm exhaust gas limit, the result can 

be three 3-hour exceedances of 10 ppm. Nonetheless, EPA believes the 

definition of 3-hour period is correct and should be retained. 

The purpose of specifying a 3-hour average for compliance with the 

10 ppm limits for exhaust gas was to improve consistency of the exhaust gas 

standards with the performance test requirements which specify an average of 

three runs of 1 hour each. The performance test method does not, however, 

preclude taking 24 1-hour samples during a 24-hour period. 

2-57 
P.67 

I . * -»v 

Rolling 3-hour periods are necessary to ensure that all 3-hour averages 

exceeding 10 ppm are reported. Otherwise, 10 ppm exceedances during two 

consecutive hours would only be averaged together if they happened to fall in 

the same 3-hour reporting period. Rolling 3-hour periods also help ensure 

timely response in correcting periods of excess emissions. In the absence of 

rolling averages, high readings during the first hour of a 3-hour period 

could be left unattended for up to two more hours without influencing reported 

results or the actions of operating personnel. 

2.5 REVISIONS TO OTHER PARTS OF THE STANDARD 

2.5.1 Exhaust Gas Standards 

Comment Lower Exhaust Gas Limit Achievability 

One commenter (IV-D-12) stated that the EPA's conclusion that the 

previously proposed 5 ppm exhaust gas limit should be withdrawn is not 

supported by the support document in this rulemaking. The commenter asserted 

that the record supports the achievability of the 5 ppm limit by new sources 

and by existing sources within 3 years of promulgation. The commenter 

pointed to the statement in the 1977 proposal that the 5 ppm limit could be 

achieved through the more efficient operation of existing equipment applied 

to either new or existing sources. The commenter also stated that the 

additional emissions reduction that would be achieved through the use of a 

5 ppm standard instead of a 10 ppm standard should not be foregone, given the 

carcinogenic nature of VC. Finally, the statement in the preamble that 

industry commenters objected to the "zero emission goal" which was the 

objective of the 1977 proposal would, the commenter stated, be counter to the 

requirement of Section 112 that an ample margin of safety be required. 

Response 

As stated in the preamble (50 FR 1184), EPA concluded during the review 

of the standard that 10 ppm reflects the level of performance that can be 

consistently achieved by primary control devices on a continuous basis. For 

this reason, the 10 ppm exhaust gas limit has been retained in the revised VC 

2-58 
P.68 

standard. In fact, however, emissions from primary control devices on a 

short-term basis are often much less than 10 ppm. These lower short-term 

emission levels would occur regardless of the level of the exhaust gas 

standards. Thus, tightening of the exhaust gas standards to 5 ppm was judged 

to be unwarranted because it would not significantly impact emissions of VC. 

The commenter presented no evidence which would warrant a revision of the 

EPA's decision. 

Comment Equipment and Work Practice R.ecuirements 

One commenter (IV-D-15) requested that the revised standard delineate 

•what degree of control equipment "backup" is acceptable for complying with 

the 10 ppm exhaust gas limits when the primary control equipment is down. 

The commenter (IV-D-16) recommended that a provision be added to the standard 

requiring a double level of redundancy for backup emission control equipment 

used to meet the exhaust gas limits. The commenter further recommended that 

backup incinerators be required to be maintained on "warm" standby and that 

flares be approved as the second level of redundancy. 

Response 

Review of enforcement and compliance experience under the VC standard 

found that most plants have installed some level of backup control equipment 

to meet exhaust gas limits. For example, discussions with four EDC/VC 

producers indicated a range of 15 to 100 percent excess incineration capacity 

availability under normal operating conditions. The five EDC/VC plants 

operated by these producers varied in the number of production units and in 

their association with larger, multi-complex chemical plants. As was expected, 

the number and configuration of backup incinerators v/as different for each 

plant. In similar discussions with two PVC producers representing seven 

plants, it was learned that in addition to incineration, solvent absorption 

is being used for both primary and backup control of exhaust gases. Again 

the number, type and configuration of backup control devices varied among the 

different PVC plants (Docket Item IV-B-1). 

2-59 
P.69 

" ^ 

Because of the inherent differences in the plants and processes to which 

exhaust gas control devices are applied, coupled with the variation in 

effectiveness of operating these devices, it is impractical to specify the 

exact amount of backup needed. Nonetheless, EPA agrees, in general, with the 

commenter's suggestions on the need for and operation of backup control 

devices. For example, backup control devices are necessary to help ensure 

control of VC emissions in exhaust gas during periods when the primary 

control device is down. In the absence of a backup control device, plants 

might have to undergo costly shutdown of process equipment each time the 

primary control device is down for scheduled or unscheduled maintenance to 

avoid violating the 10 ppm exhaust gas limits. Even when backup control 

devices are available, exceedences of the 10 ppm exhaust gas limit are 

possible. However, plants must analyze and identify ways of operating their 

primary and backup control systems to improve the ability of the combined 

systems to continuously control exhaust gas emissions. Thus, because it is 

impractical to specify the degree of backup needed in the standard. 

Comment Specification of 3-Hour Averaging Period in 

Exhaust Gas Standards 

Two commenters (IV-D-1, IV-D-4) recommended that the 3-hour averaging 

period be specified in three sections of the regulation where 10 ppm limits 

were not clarified by indicating a 3-hour averaging period. 

Response 

As explained in the preamble to the proposed revisions (50 FP. 1192), the 

exhaust gas standards should appropriately specify a 3-hour average to be 

consistent with the performance test specifications for these emission 

sources. 

The three sections of the regulation pointed out by the commenters have 

been revised as recommended. 

2-60 
P.70 

v , * 

2.5.2 Oxychlorination Vent Standard 

Comment Withdrawal of Lower Oxychlorination 

Vent Standard 

The commenter (IV-D-12) pointed out that the 1977 proposal would have 

required new oxychlorination vents to meet an emission limit of 5 ppm based 

on the use of oxygen, as a feed material instead of air. The commenter stated 

that EPA has failed to present any discussion which would justify the 

withdrawal of this proposal. 

Response 

In the preamble (50 FR 1185), EPA presented evidence supporting its 

decision not to require more stringent control of new and existing oxychlorination vents. First, the review of the standard identified no new control 

technology applicable to oxychlorination vents that had been developed since 

the original standard was established. Second, the cost to incinerate 

existing oxychlorination vents was reevaluated, and the conclusion of the 

original standard support study (Docket Item II-A-2) that incineration of 

existing oxychlorination vents is not cost-effective was sustained in the new 

analysis. Finally, with the possible exception of one plant, new EDC/VC 

plants with oxychlorination reactors are not expected to be constructed. 

However, if constructed, a new plant would be subject to the New Source 

Performance Standards for air oxidation processes or to BACT or LAER requirements of new source review regulations. As a result of these regulations, 

new oxychlorination vents would be controlled to a level consistent with the 

10 ppm exhaust gas limits in the VC standard. 

No information was provided by the commenter to change the EPA's decision 

to retain the existing oxychlorination vent standard. 

Comment Specification of 3-Hour Averaging Period 

in Oxychlorination Reactor Standard 

Two commenters (IV-D-1, IV-D-4) recommended that the 3-hour averaging 

period be specified in the emission limit for oxychlorination reactors. 

2-61 
P.71 

l , .p • » • 

Response 

As explained in the preamble to the proposed revisions (50 FR 1192), the 

exhaust gas limits should appropriately specify a 3-hour average to be consistent with the performance test specifications for these emission sources. 

This is also true for the oxychlorination vent limit. The oxychlorination 

reactor standard has been revised as recommended. 

2.5.3 Residual Vinyl Chloride Standards for PVC P.esins 

Comment Withdrawal of Lower Stripping Requirements 

One commenter 'IV-D-12) stated that EPA withdrew the proposed reduction 

in the residual VC limits for new PVC resins because it was determined that 

only some resins can now be stripped to these levels. The commenter asserted 

that this conclusion is based on the assumption by EPA that an emission level 

must be currently demonstrated to form the basis of the standard, but according 

to the commenter, that demonstration is not required by Section 112. Further, 

the commenter stated that the lower limits are currently being achieved by 

many PVC production facilities and that many of the remaining facilities are 

close to the limits. The commenter stated that the more stringent limits 

could be achieved by new facilities, as well as by existing facilities if 

given a three year lead time, by copying the equipment and procedures currently 

used by the leading facilities. 

Response 

As discussed in the preamble (50 FR 1185), EPA rejected more stringent 

stripping level requirements for new resins primarily because of the difficulty 

in defining a "new" resin. Although resin compositions are adjusted routinely, 

completely "new" resins are seldom if ever made. 

The EPA further concluded that there is insufficient technology basis 

for more stringent stripping requirements for all resins. In particular, 

improved stripping technology is capable of lowering residual VC levels in 

only some of the resins currently produced. The ability of improved stripping 

technology to achieve lower residual VC levels depends on the resin type and 

mix at a particular plant. The equipment and procedures that are effectively 

2-62 
P.7 2 

. <•«." . ' 

being used to strip a specific resin may be ineffective on another resin. 

Many plants already use improved technology where applicable to average out 

the stripping levels achieved for hard-to-strip resins. This technique of 

averaging the stripping results of hard-to-strip resins with resins that are 

more readily stripped allows these plants to comply with the current residual 

VC standard while continuing to produce the hard-to-strip resins. Increasing 

the stringency of the residual VC standard for all resins would, in the 

opinion of EPA, force some plants to discontinue production of some resins 

unreasonably. The commenter submitted no new information on that point. 

.2.5.4 Reactor Opening Loss Standard for In-Reactor-Strippers 

Comment Compliance Waiver Request 

The commenter (IV-D-3) stated that the proposed calculation procedure 

for determining reactor opening loss for reactors used as strippers may 

necessitate installation of more accurate instrumentation. He requested that 

the regulation provide for waivers of compliance to allow time to select, 

order and install additional instruments. 

Response 

The calculation procedure for determining reactor opening loss emissions 

for reactors used as strippers provides plants that perform in-reactor 

stripping an optional method for demonstrating compliance with the emission 

limit for reactor openings. Plants using the calculation procedure will be 

required to continue their current practice for demonstrating compliance 

while selecting, ordering, and installing the instruments used'to measure the 

reactor conditions necessary for calculating reactor opening loss. 

Comment Status of Previously Approved Methods 

The commenter (IV-D-1) noted that the proposed emission testing 

requirements for reactors used as strippers appear to require all stripping 

operations with approved calculation methods to resubmit their calculation 

methods for approval and questioned whether resubmittal of already approved 

methods was intended. 

2-63 
P.73 

Response 

The EPA developed a calculation procedure for determining reactor 

opening loss emissions from reactors used as strippers to provide a uniform 

method for use by all plants that perform in-reactor-stripping. However, 

plants may continue to determine reactor opening loss emissions from reactors 

used as strippers by previously approved methods. Resubmittal of already 

approved methods is not required. However, Regional personnel may review 

these previously approved methods in light of the newly prescribed calculation 

procedure and require changes in existing procedures where appropriate. 

.2.5.5 Inprocess Wastewater Standard 

Comment Request for Approval of Method 601 

Two commenters (IV-D-8, IV-D-9) suggested that the VC standard allow 

either Method 601 or the currently required Method 107 for measuring the VC 

concentration in inprocess wastewater. The commenters explained that Method 

601 has a detection limit of 0.01 g/1 (0.01 ppb) and should, thus, be 

acceptable for inprocess wastewater measurement. 

Response 

Method 601 of 40 CFR 136.3(a) is acceptable for measurement of VC in 

inprocess wastewater, and 40 CFR 61.67(g)(2) has been amended to allow its 

use. 

2.5.6 Equivalent Equipment and Procedures 

Comment Status of Previously Granted Equivalencies 

Two commenters (IV-D-8, IV-D-9) recommended that the provision on 

obtaining approval for equivalent equipment and procedures indicate that 

previously granted equivalencies will remain in effect for existing facilities, 

Response 

Any Agency approval previously given to equivalent equipment and 

procedures pursuant to Section 61.66 will remain valid and effective unless 

they are specifically modified or withdrawn by EPA. Alternative numerical 

2-64 
P.74 

emission limits cannot be granted in place of an established emission limit, 

but only alternative means of emission limitation. 

2.6 MISCELLANEOUS COMMENTS 

Comment Regulatory Flexibility Act - Small Business 

Definition 

The commenter (IV-D-3) stated that EPA incorrectly concluded that nc 

small business (i.e., less than 500 employees) is affected by the proposal. 

The commenter's subsidiary PVC company has 300 employees. 

Response 

In response to the comment there are three points that are important. 

The first point is that at the time the economic analysis (Docket Item IV-B-11) 

was performed the commenter's company did not exist. 

The second point is that the Regulatory Flexibility Act (RFA) defines a 

small business based upon the size of the total company including the parent 

company plus all subsidiaries, rather than the size of individual subsidiaries 

or individual plants. The commenter's assertion that it is a small business 

referred only to the size of a subsidiary and not to the total company. 

Later information provided in response to questions from EPA shows that the 

total company is not a small business because it has more than 500 employees. 

The third point is that size alone is not the only test in assessing the 

need for a regulatory flexibility analysis. Significant economic effects 

must also be likely, otherwise a regulatory flexibility analysis is not 

required. The EPA does not expect such effects. Therefore, for the reasons 

cited above, the regulatory flexibility discussion currently in the economic 

analysis in the BID does not require any changes. 

Comment Economic Impact of Standard 

The commenter (IV-D-3) stated that costs required to comply with the VC 

standard have a negative impact on the industry's profitability and competitive 

situation in regard to foreign producers. 

!-6E 
P.75 

f , >P Ns 

Response 

The commenter discusses three subjects in its comment and its 

supplementary information: 

• the general economic condition of the domestic VCM/PVC industry 

» the economic condition for the commenter's facility specifically 

(but with only a limited amount of supporting financial information; 

• the foreign competition. 

The economic analysis presently available (Docket Item IV-B-11) includes 

consideration of the above subjects (with the exception of information 

specific to the commenter's facility because it did net exist at the time). 

Consideration of the general economic condition of the domestic industry runs 

throughout the analysis. Foreign competition is also specifically discussed 

in Section 8.1.8. More than 2 years have passed since the economic analysis 

was completed, sc naturally changes have occurred.in the industry during the 

interim. However, the new information supplied by the commenter about the 

industry in general and about foreign producers is not significantly different 

from what is currently in the economic analysis. Overall, the economic 

analysis appears to be reasonable in addressing the impact of the VC standard 

on the VCM/PCV industry. 

The financial information presented by the commenter concerning its 

specific situation is insufficient to permit a detailed examination. Also, 

because the firm is only about 1-1/2 years old, its young age sharply limits 

the value of an analysis of historical financial performance. Two points 

indicate that the current economic analysis is reasonable. The first point 

is that, in general, the commenter's situation seems to be reasonably similar 

to the model plant analysis presented in the economic analysis. For example, 

a calculation of the cost increases per kilogram of capacity indicates that 

the cost increases presented are approximately the same as those for the 

model plants. The second point is that the owners and managers of the 

commenter's facility are not newcomers to the industry. Therefore, because 

the owners and managers had a high degree of prior knowledge about the 

industry, considerable importance should be attached to the fact that they 

elected to proceed and purchase the plants in question as recently as 

July 1984. 

2-66 
P.76 

Comment VC Emissions from Landfills 

The commenter (IV-D-10) agreed with the EPA's approach of requiring 

plants that generate off-specification PVC resins to meet standards designed 

to facilitate'the ultimate disposer of the off-specification resin in complying 

with the environmental regulations applicable to hazardous waste disposal. 

The commenter expressed concern that stripping requirements for of**--

specification PVC resins prior to removal to landfills may not be sufficient 

to prevent subsequent exceedences of the proposed drinking water standard for 

VC. The commenter explained that VC contamination of drinking water is 

likely because PVC resin is not legally a hazardous waste and'is therefore 

not required to be disposed in facilities regulated under Subtitle C of the 

Resource Conservation and Recovery Act (RCRA). The commenter urged EPA to 

better coordinate all regulatory activities pertaining to VC. 

Response 

This rulemaking is limited in scope to the regulation of atmospheric 

emissions of VC from off-specification PVC resins in landfills. In this 

context, the stripping requirements in the standard for off-specification PVC 

resins are believed to be the most effective way of limiting VC emissions 

from PVC resin in landfills. If there are other environmental consequences 

of the disposal of off-specification PVC resins, appropriate restrictions can 

be applied under other statutes. 

Comment Offer to Assist RCRA. Task Force 

The commenter (IV-D-1) offered to provide assistance to the Task Force 

established under Subtitle D of RCRA in their assessment of emissions of VC 

from hazardous waste facilities, municipal landfills and other air emission 

sources. .Further, he requested that his organization be kept informed on the 

task force's activities. 

Response 

The commenters' request has been forwarded to the RCRA Task Force. 

• 67 
P.77 

r. ix . 

Comment Reporting of Design Capacity 

The commenter (IV-D-3) stated that the requirements in proposed 40 CFR 

61.70(f) for plants to report design capacity information is inappropriate as 

this information is proprietary. Further, plants that strip in the reactor 

should not be required to provide design capacity information because it is 

irrelevant, for compliance determination,..and other plants should be allowed to 

provide design capacity in a separate confidential document. 

Response 

The information being requested in this provision of the standard is the 

design capacity of a PVC plant in terms of an estimate of the number of 

polymerization batches the plant is capable of producing, rather than specific 

batch sizes or rates. Such information would not reveal significant information on actual production and, consequently, would not ordinarily involve 

confidentiality problems. However, if the owner or operator of an affected 

facility has reason to believe that this or any other information submitted 

to EPA should be treated as confidential, such treatment can be requested at 

the time of submittal and a decision on the request can be made by EPA. 

In the case of plants that strip in the reactor, no reporting of design 

capacity data is required. For the added compliance method for in-reactorstrippers, plants need only report VC emissions calculated to be in excess of 

the combined limit for reactor opening loss and sources following the stripper. 

Information on design capacity needed for the calculation method need only be 

retained at the plant in the records for compliance calculations. 

Comment CERCLA Reporting Requirements 

Three commenters (IV-D-1, IV-D-6, IV-D-14) requested clarification on 

the applicability of the Comprehensive Environmental Response, Compensation 

and Liability Act (CERCLA) reporting requirements to sources regulated under 

the VC standard, specifying whether VC releases from EDC/VC and PVC plants 

are required to be reported under CERCLA. Commenter IV-D-14 specifically 

questioned whether emissions below the threshold concentration defining an 

actionable leak are intended to be reported under CERCLA. A third commenter 

2-68 
_• «' ,1 

, •-! ' 

(IV-D-12) stated that relief valve discharges of VC are reportable under 

CERCLA, except to the extent, that they are the result of a genuine emergency. 

Response 

Under the provisions of CERCLA, releases of hazardous substances which 

are federally permitted are not subject to CERCLA. notification requirements 

and liabilities. The definition of "federally permitted release" in Section 

101(10) of CERCLA specifically includes ". . .(H) any emission into the air 

subject to a permit or control regulation under . . . Section 112 .. . of 

the Clean Air Act ... " therefore, emissions in compliance with this standard 

are not subject to CERCLA. However, emissions exceeding this standard and 

the reportable quantity provisions of CERCLA are subject to both statutes. 

Comment Reporting and Recordkeeping Requirements 

Four commenters (IV-D-3, IV-D-8, IV-D-12, IV-D-13) addressed the proposed 

reporting and recordkeeping requirements. The first commenter (IV-D-3) 

disagreed with the EPA estimates that the annual paperwork burden will be 

reduced by 2.8 person years by the proposed revisions. The commenter claimed 

that the inclusion of the Subpart V requirements would necessarily increase 

the paperwork burden. The second commenter (IV-D-8) stated that the proposed 

changes in reporting requirements represent an emphasis on emission reduction 

rather than increasing paperwork. The third commenter (IV-D-12) stated that 

all test results should be reported, not just those that exceed the standards. 

Such a requirement would promote accuracy and completeness and permit EPA to 

build a data base for future revisions of the standard. 

Response 

The reporting and recordkeeping burden resulting from the revised 

standard was evaluated by EPA using standard Agency procedures to arrive at 

the estimate that the burden would be reduced by 2.8 person-years. Basically, 

this estimate reflects the reduction in reporting and recordkeeping requirements in the revised standard. The calculations on which this estimate is 

based have been reviewed by OMB as a part of the Information Collection 

2-69 
t , t *-»-

•» t-J-* t 

Request, which is available for inspection in the docket (Docket Item IV-F-1). 

The ccm.menter has suggested no specific errors in this analysis nor recommended 

an alternative analysis. 

The submission of all test data associated with the standard has not 

been required because such a requirement would impose an unnecessary burden 

on both the respondent and EPA. It is mere productive to check into the 

accuracy and completeness of calculations as the need arises (using the 

authority of Section 114) than to handle a quantity of routine reports. The 

calculations are required to be maintained for a 3-year period. Further, an 

adecuate data base for future review of the standard can be obtained without 

such extensive commitment of resources to reporting. 

Since proposal, EPA decided to retain 10-day reporting requirements for 

relief valve discharges. In addition, quarterly reporting of excess emissions 

will be required instead of semiannual reporting., as proposed. The net result 

of the promulgated changes to reporting and recordkeeping requirements is not 

expected to significantly increase or decrease the paperwork burden compared 

to the existing standard. 

Comment Typographical Errors 

Five commenters (IV-D-1, IV-D-3, IV-D-6, IV-D-8, IV-D-9) pointed out 

typographical errors in the Federal Register notice. 

Response 

The typographical errors have been noted and those contained in the 

regulation will be corrected at promulgation. 

2-70 
I ' . *• 

3.0 PETITION FOR RECONSIDERATION 

In response to the EPA's notice that the Agency did not intend to 

promulgate the amendments to the VC standard which were proposed in 1977, the 

Natural Resources Defense Council (NRDC) and the Environmental Defense Fund 

(EDF) submitted a petition for reconsideration to the Agency. 

The NRDC/EDF petition was based on four main objections. First, NRDC/FDF 

stated that the EPA's announcement that it did not intend to promulgate the 

proposed amendments was a final administrative action, which was not preceded 

by a notice proposing the withdrawal and allowing for public comment on the 

action. Second, NRDC/EDF objected to the EPA's use of cost information in 

the standards setting process, stating that the balancing of the costs and 

benefits of VC emissions control is in conflict with the requirements of 

Section 112 of the Clean Air Act. Third, NRDC/ETJF objected to any interpretation of Section 112 that establishes a requirement that a level of emission 

control be "consistently achieved" in order to form the basis of a standard. 

Finally, NRDC/EDF stated that the EPA's decisions on specific portions of the 

proposed amendments were in conflict with the evidence before the Agency on 

those issues. 

The criteria established for granting such a petition for reconsideration 

are: (1) the petition must be based on information which was not and could 

not reasonably have been presented during the original rulemaking; and (2) 

the petition must provide substantial support for the argument that the 

challenged action should be changed. See Denial of Petition to Revise NSPS 

for Stationary Gas Turbines, 45 FR 81653 (December 11, 1980). The objections 

raised in the petition submitted by NRDC/EDF in this rulemaking do not meet 

either criterion. 

The first objection raised by NRDC/EDF, that there was inadequate 

opportunity for public comment concerning the Agency's decision not to 

3-1 
P.81 

1 , > •*-

promulgate the proposed VC regulations, is not supported by the record of 

this rulemaking. Between the proposal of the amendments to the VC standard 

and the decision not to promulgate them, 8 years have elapsed. During this 

time, the amendments, their potential consequences, and the alternative 

actions before the Agency were all in the public record, and specifically 

communicated to NRDC and EOF prior to the NAPCTAC meeting. In light of this 

record, EPA does not believe that an additional public comment period would 

be either necessary or helpful in the resolution cf these issues. 

The second issue raised by NRDC/FDF in the petition for reconsideration 

concerned the consideration of costs of control in setting the standard. It 

is the EPA's judgment that the VC standard satisfies the requirement of 

Section 112 of the Clean Air Act that the standard be set at a level which 

provides an "ample margin of safety" to the public. Further, EPA believes 

that cost and feasibility may be considered in setting the standard. This 

argument has been fully examined by the Agency, as discussed in the 1975-1976 

VC rulemaking and discussed in the Agency's brief in NRDC v. EPA , No. 85-1150 

(D.C. Cir). No additional information in support of their argument has been 

put forward by NRDC/EDF. 

The third issue raised by NRDC/EDF concerns whether an emission level 

must be "consistently achieved" in order to form the basis of the standard. 

This issue was raised with specific reference to the 10 ppmv standard for 

exhaust gas VC emissions. This standard was selected because it was determined 

that it provides the public with the ample margin of safety required by 

Section 112. Although a lower emission limit might be assumed to increase 

that margin, such a level has not been shown to be achievable on a long-term, 

never-to-be-exceeded basis. No additional information has been submitted by 

NRDC/EDF to refute the finding that the 10 ppmv emission limit for exhaust 

gases provides the required margin of safety for the public. 

Finally, the petition points to three actions made by the Agency in this 

rulemaking which NRDC/EDF believe to be contrary to the evidence before the 

Agency on those issues. These actions are: (1) the decision not to promulgate 

the 5 ppmv standard for exhaust gases in favor of the existing 10 ppmv 

standard; (2) the decision not to promulgate the 5 ppmv standard for 

3-2 
P.82 

oxychlorination vents; and (3) the decision not to lower the residual VC 

limit for new dispersion resins from 2,000 ppm to 500 ppm, or to lower the 

limit for other resinsfrom 400 ppm to 100 ppm. In each case, the petitioners 

presented no new information in the petition for reconsideration relevant to 

the decision to retain the existinn standards. 

3-3 
P.83 

*:••'« 

TECHNICAL REPORT DATA 

(Please read Instructions on the reverse before completing) 

1. REPORT ,\I0. 

EPA 450/3-86-004 

3. RECIPIENT'S ACCESSION NO. 

4. TITLE ANO SUBTITLE 

Vinyl chloride standard: Responses to Comments on 

January 1985 Proposed Revisions 

5. REPORT OATE 

September 1986 

6. PERFORMING ORGANIZATION CODE 

7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT \ i 

9. PERFORMING ORGANIZATION NAME ANO ACORES3 110. PROGRAM ELEMENT '.O 

2. SPOiNSORlNG AGcNC v NAME ANO ADDRESS 

Office of Air and Radiation 

U.S. Environmental Protection Agency 

Washington, D.C. XXoO 

,13. TYPE CF Fi=.PQRT ANO F = = i 

I 

i 1A. SPONSORING AGENCY CODE 

15. SUPPLE.ME.NTAR Y NOTES 

16. ABSTRACT 

This document summarizes and responds to comments on the proposed revisions 

to the vinyl chloride standard set under Section 112 of the Clean Air Act. 

KEY WORDS ANO DOCUMENT ANALYSIS 

DESCRIPTORS b.lOENTIFlERS/OPEN ENOED TERMS c. COSATI '•'idil/Group 

NESHAP 

Hazardous Air Pollutants 

Vinyl chloride 

18. DISTRIBUTION STATEMENT 

Unlimited 

19. SECURITY CLASS /This Report) 

Unclassified 

2 1 . OF PAGE 

120. SECURITY CLASS iTIiispa.nei 

I Unclassified 

122. PRICE 

EPA Form 2220-1 (Rev. J-77) =BEVIOU S EDITIO N IS OBSOLET E 
United SUHHS 

Environmental Protection 

Agency 

l Uin <• n( Air .KM! K;idi;iH--ii 

OHif.i! of Air Ounhiy ri;iniitmj ;*nd Standards 

Research lri.niiile Patk. North C.nrolina 2771 1 

Olftciaf Business 

Finall y for Private Use 

s.ioo 

If your address is incorrect, please change on the above lahel; 

tear off; and return to the above address. 

If you do not desire to continue receiving this technical report 

series. CHECK HERE G ; tear off label; and return it to the 

above address.